Here is the list, according to Business F1 and reproduced by GP2003.com:
Michael Schumacher 32 million Ralf Schumacher 14 million Juan Pablo Montoya 12 million Kimi Raikkonen 8 million David Coulthard 8 million Fernando Alonso 6.3 million Jarno Trulli 6 million Rubens Barrichello 5.5 million Olivier Panis 4.5 million Cristiano da Matta 4 million Jenson Button 3.7 million Giancarlo Fisichella 3 million Mark Webber 2 million Felipe Massa 1.5 million
Unfortunately GP2003.com foolishly neglects to provide a unit for all of this.

Notable bargains: BAR drivers (Jenson at 3.7 and Takuma -- who supposedly brings Honda sponsorship) and Webber (2 million). Perhaps even Massa at 1.5million.
Other notables: Nick Heidfeld is not on this list.