I read a benchmark somewhere that tested the 8800GTS 320 in Oblivion on max at 1920x1200 with 4xAA 16xAF, HDR and it performed within 2 FPS of the 640MB version.
Oh It's because I dont live in there so I wouldnt know, Well I guess that card would be good, and what wolf said about not putting like AA x80 and 16000x12000 then 300mb would be good enough, I have 256 on all my cards and I can run all the stuff good
Inno3D is a good brand and their i-Chill 7900GS was rated Best Hardware by Guru3D. It comes with an Arctic Silencer cooling fan, so that should speak volumes about their reputation.