For David Coulthard to have any chance of catching Michael Schumacher in the title fight he knows that he must win at Silverstone. And if he does win it will be his third win at Silverstone in a row. Only Jim Clark has managed to win the British GP 4 times in a row (1962 - 1965) and no other driver has won it more than twice in a row..
At the Silverstone test (test times) last month McLaren were fastest however in the last 3 races McLaren were slower than both Ferrari and Williams so it will be hard to predict how close McLaren will be to the Ferrari and the Williams in the race. 
At the French GP, Coulthard made a mistake by speeding in the pit lane, a mistake that at least cost him second place if not a win. Another problem that McLaren have is their dreadful starting record with 5 start related failures so far this season. Coulthard cannot afford any mistakes and will need a perfect car if he is to challenge for the win.

Ferrari: With a massive 52 point advantage over their nearest rivals and an excellent reliability record, they seem unbeatable and it will take a miracle for McLaren or Williams to catch them.
The only problem that Ferrari might have is a smaller fuel tank (or a thirstier engine) which could affect their pit stop strategy.

Reliability 9.5/10 - Speed 9.5/10

Drivers: Michael Schumacher has won 6 races, finished 2nd in 3 and retired once. He has capitalised on the failures and mistakes of the others and at the moment he is unbeatable.
His car has been impressive as well so he is certainly the favourite to win although he has not been as impressive at Silverstone as at some other races in the past. Expect a top 3 finish with a win a big possibility.

Rubens Barrichello has lost 3rd place in the drivers' championship to Ralf Schumacher and he doesn't appear to be even close to his team-mate. He had his worst qualifying in France only managing 8th on the grid and benefited from the retirements ahead of him to finish 3rd. A top 6 finish is possible. 

McLaren: If they continue with their start problems, Williams will certainly take second place away from them. They also appear to lack the pace of both Ferrari and Williams and will have to work extra hard if they want to close the gap to Ferrari.

Reliability 7.0/10 - Speed 8.5/10

Drivers: David Coulthard cannot afford any mistakes and needs a reliable car. If that happens then he could win the race for the 3rd time in a row. He must win if he wants to keep his title chances alive. A top 3 finish is possible. 

Mika Hakkinen had his 5th retirement of the season in France and speculation of his retirement from Formula 1 is growing. He'll need to squash those rumours if they are just rumours by doing well at Silverstone. He could finish in the top 3 although a top 6 finish is more likely. 

Williams: It appears that the advantage of the Michelin tyre has disappeared. At the French GP, Ralf struggled with his second set and ended up finishing 2nd after his team-mate retired and Coulthard was penalised. They weren't quick in testing at the Silverstone test last month but one cannot draw too many conclusions from testing. They will still be a force to reckon with regardless of the tyre situation but they need to get better reliability.

Reliability 7.0/10 - Speed 9.5/10

Drivers: Ralf Schumacher finished second at Magny Cours making it his 3rd points finish in a row. He has been far more consistent than his team-mate and if he continues that way he will close in on Coulthard who is only 16 points ahead of him. A top 6 finish is likely.

Juan Pablo Montoya another retirement but this time due to an engine failure. He has so far only finished 2 races this season and that is not a good record. He should qualify closer to his team-mate here as he is familiar with the track. If he doesn't retire then he'll finish in the top 6.

Sauber: Remain ahead of Jordan in the championship thanks to a reliable car and two very good drivers. They are fighting with Jordan and BAR for the best of the rest position in the championship and given the problems at Jordan and BAR they could do it. They will be disadvantaged here at Silverstone as it is not their testing track.

Reliability 8.0/10 - Speed 7.5/10

Drivers: Nick Heidfeld finished in the points in France making it his 4th points finish of the season and considering that there are 3 teams and 6 drivers that have superior cars, this is a great achievement from the young German. A top 6 finish will be very hard though as Jordan and BAR will have the home track advantage.

Kimi Raikkonen has managed to finish the last 6 races which is impressive for a rookie. He is just 2 points behind his team-mate and given the opportunity he could beat him. It is unlikely to happen at Silverstone though given the tough competition from the other teams. A top 10 finish is likely. 

Jordan: Have finally managed to score some points in the last race after failing to score any in the previous 4. They will have a good chance of scoring some more here if one or more of the top 3 teams face problems. BAR will be strong though and the fight between the 2 here will be intense.

Reliability 5.0/10 - Speed 8.0/10

Drivers: Jarno Trulli qualified an impressive 5th in France ahead of a Williams and a Ferrari. He also finished in 5th place and has scored 3 points more than his team-mate so far this season. If a Jordan scores points at Silverstone it will most likely be Trulli. Could finish in the top 6 even if the top 3 teams all finish.

Heinz Harald Frentzen appears to have slowed down as he is not doing well in qualifying or in the race. The last time he finished in the points was at San Marino, since then he retired 4 times, didn't race in one and finished 8th in the last race. If all the Honda runners finish at Silverstone expect Frentzen to be the last of them. A top 10 finish is possible.

BAR: The last time they scored points was at Monaco. For the last 3 races the best finish they had was 9th!. Their qualifying is not any better as the Jordan Honda seems to beat them consistently. It will be a tough second half of the season for them. 

Reliability 6.5/10 - Speed 8.0/10

Drivers: Jacques Villeneuve retired with an electronics problem at Magny Cours. He must be frustrated with the situation at BAR and would move if there are available seats at one of the top teams. The frustration is not helping him but he has managed to out-qualify his team-mate in the last 2 events. He could finish in the top 6 if one of the top 3 teams run into problems although he will have to also compete with Trulli and his own team-mate.

Olivier Panis managed to finish the race in France following 3 retirements before. He is strong at Silverstone having tested there so many times. He could qualify as the best Honda runner and could also finish in the points.

Jaguar: Following their strong showing at the Nurburgring, they didn't do well at Magny Cours with a retirement and a 14th place. Their package still needs a lot of work if they are to catch the 3 teams ahead of them.  

Reliability 7.5/10 - Speed 7.0/10

Drivers: Eddie Irvine is probably driving at his best in his career but his car is not helping him. We have seen him make daring overtaking moves in France but in the end his engine failed him. A points finish is unlikely.

Pedro de la Rosa was expected to be close to if not faster than Irvine. He has not shown that yet. Perhaps it is the lack of experience in the Jaguar, we'll just have to see. A top 10 finish is possible.

Prost: Appeared to have made some improvements similar to Jaguar but not on all the tracks. They don't test at Silverstone regularly so that will put them at a disadvantage. They will be competing with Benetton and Arrows.

Reliability 9.0/10 - Speed 6.5/10

Drivers: Jean Alesi struggled at his home GP all weekend and was out-qualified and out-raced by his rookie team-mate Burti. It appears that the modifications suited Burti's style more than Alesi's. A top 10 finish will be difficult.

Luciano Burti is certainly proving a tough opponent for Alesi and could once again beat him here. A top 10 finish will be difficult for either Prost.

Arrows: Were beaten by Prost at Magny Cours as they now appear to seriously struggle with the power of the AsiaTech motor they use. The rest of the season does not look good for them.

Reliability 5.5/10 - Speed 5.5/10

Drivers: Jos Verstappen managed to finish 13th at Magny Cours and that was the best he could do. A top 10 finish is unlikely.

Enrique Bernoldi will probably not make it back to Formula 1 next year, whether it is due to his own mistakes or his car, 3 finishes out of 10 races is not a good record. He must be feeling the pressure and will struggle again to finish.

Benetton: The wait is over but the speed is still not there!. Qualifying in 16th and 17th is by no means a big step forward!. Don't expect them to do much better at Silverstone and if they don't improve before the end of the season, expect serious changes at Benetton.

Reliability 6.5/10 - Speed 4.5/10 

Drivers: Giancarlo Fisichella finished 11th at Magny Cours and 11th at the Nurburgring so what did the new engine do for him ? Expect a similar result at Silverstone. 

Jenson Button needs to get closer to Fisichella otherwise he will be loaned to yet another team. This is not helping his career and he better start working on improving. The car is not helping though and a finish inside the top 10 would be a big achievement!.

Minardi: They seem to be alone at the back although Arrows don't appear to be much faster. With the high rate of finishers, their hope of finishing in the points is almost nil. 

Reliability 5.0/10 - Speed 4.0/10

Drivers: Fernando Alonso yet again retired from the race at Magny Cours due to a problem with his car. He certainly needs a better car to show his skills. It will be very hard from him to finish in the top 10.

Tarso Marques was just under half a second slower than Alonso in qualifying at Magny Cours. He must be feeling the pressure to perform or else. Malaysian Alex Yoong is waiting and if Marques doesn't pick up his game he'll be out before the season ends. It will be good if he finishes.