I'm not well-versed with Asus products, but I do know that there are two different GF2GTS Pro cards. One has 32mb of ram and the other has 64mb. The 64mb Pro is an excellent buy at about $140-$150. It has about 80% of the performance of an Ultra (still not an Ultra, though!) for about 1/2 the price.
I have a 32mb GTS...plain jane. I'm personally waiting for the GF3 prices to hit about $250, then I'll buy one. Right now $300 for a video card is too much. For that price, I could get a complete DDR system! (mobo/CPU/RAM)