9600GT:
Max's the mod+crysis rather well, only about $100 (or less). Get the 512MB version.
You might have to do a tad bit of tweaking or sacraficing on SOME visuals if you want to run at higher FPS (25-35 FPS usually on max), but it's not bad. I run at 1320x780 widescreen resolution.
And yes, 1GB of video-memory is a waste. Remember that cards with lots of video memory don't mean shit... what's most important is the amount of processing power, the pipes, etc in the card NOT the memory it has. You'll want atleast 512MB of video memory but any more than that is a waste, especially since many games won't even use the full 512MB and can even rune fine on 256MB (which is decent as well but not reccomended as higher textures or higher resolutions will stutter on it due to the more limited space).