Actually, when it comes to buying graphics cards; which brand matters little as they are all based on the same reference design. The differentiating factors are in:

. memory speed used: some vendors claim to use "faster" memory although usually it's just a factory overclock

. custom coolers: although for the 8800GTX these have yet to surface. Careful though, stock coolers have been known to perform better than the custom cooler.

. bundled software / hardware. Asus likes to bundle a webcam, sometimes the games included are pretty good. Generally however the freebies are crap-in-a-box.

To me however, a buying decision is based on level of support. I need to be sure that should the card develop problems I'll have no problems swapping it for a working version. This depends on the shop you bought your card from and/or the local distributor.