~BUMP~
Yeah buy the 640 or wait for HD2900XT. Personally the HD2900 would be my choice (and that's coming from a hard-core Nvidia Fanboy) but whatever way you go, don't get the 320MB. My 8800 320 runs really great, but if it ever runs out of texture RAM (such as in STALKER or Oblivion) it stops cold to load more textures. Very disappointing if you ask me.