hate to burst your bubble but it is correctly identified. the 2900GT only has 240 Shaders, 120 have been disabled unlike the 2900PRO the GT is pretty much a XT cut in half then thrown on a PCB board. it's comparable to the 8600GTS and even losses sometimes to the 8600GTS.
for $120 i guess its not the bad of a board for the price seeing as it totally kills the weakling 2600XT/PRO(For the same price and even cheaper in some chases)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814102712
i would google and check some mods or Bios out, maybe, you can get the 240 Stream units unlocked to 320 who knows?