Re: French Open 2008
It is normally six weeks before the tournament starts, so we're looking at the rankings of the 14th of April (I think, please correct me if im wrong). So thats basically the week of Charleston.
12 qualifiers and 8 WCs, so that leaves around 108 players automatically qualify for MD (however some use special rankings so that can change). But basically if you are in the Top100 you are more or less guranteed a main draw place.
96 Qualifying Draw players.
So in answer to your question, its the Top200 that will play MD and QD.