the top speed difference is 339 for Schumacher compared to 333 for both Mclarens.
compare this with 347 for Senna,334.5 for Webber,332 for Trulli,329.5 for Kovalainen and 327.4 for Vettel...
obviously Vettel had enough Horsepower to win the race and drive at a very competitive speed laptimewise the quickest laps of Senna and Vettel differed only by 3tenths of a second but their Topspeeds were 20kmh apart.
Hamilton and Button had 6kmh less on the straights but 1.2 seconds better laptimes over Schumacher ...so gearingwise they were not that far from each other but Schumacher has a fair bit less drag so is reaching his slightly better top speed much earlier.
I think this is explaining what we saw well enough .
Button is confirming this in his post race analysis:
http://www.motorsport-total.com/f1/news ... 91151.html
They were running out of revs on the pit straight ,but the shorter gearing was a big advantage in the run to Ascari .