I went out and bought one of those nice new BFG 8800 GT OCs. It runs wonderfully and I can play in higher settings and get much improved frame rates in most every game I play. Except the game I really wanted it for: EverQuest II.
Eventually I want to get a more modern gaming rig, with SLI, and a quad core CPU. But EQ II doesn't support that either.
I guess that's the problem with designing your system "for the future." It never quite gets here.