Go for the GF2 Pro 64MB, it's less then 150$ on PriceWatch.com. Little over with shipping. If you had to get the 32MB model it would be a tough call, as games that used less then 32MB of VRAM would be faster on the Pro, and newer games that used more then 32MB of VRAM would be faster on the Radeon 64MB.
But you can get the GTS Pro 64MB, so it's not. Go with the Pro.