ATI Radeon HD 2900 XT Performance Benchmarks
 

The benchmarks were conducted on an Intel D975XBX2 BadAxe2, Intel Core 2 Extreme QX6700 and 2x1GB DDR2-800 MHz. The operating system on the test system was Windows XP, with a fresh install before benchmarking each card. Testing of the AMD ATI Radeon HD 2900 XT was performed using the 8.361 Catalyst RC4 drivers, while the GeForce 8800 GTS used ForceWare 158.19 drivers.

http://www.dailytech.com/article.aspx?newsid=7043

I hope there will be enough HD 2900 XTX available at launch, because the HD 2900 XT priced at ~$499 doesn't seem capable of beating the 8800 GTX

it does great as a pro card tough

but not at $499 price :(
GTX is $550