Re: What's your racquet size?
Alot of Spanish players use small sizes (4 1/4) for better topspin e.g Nadal, Coria, Verdasco.
I also believe Ancic uses 4 1/4. Federer is a 3/8 and Roddick is around about a 1/2 but it's totally custom. As is Hewitt's, he has his customised by Bosworth to be around an L6-7.
I use a 3/8, technically I should be a 1/2 but the 3/8 gives better feel and spin if you can middle it often. if you can't then you are going to get alot of nasty twisting in your hand.