q[Never buy a video card before or right when a graphic / processor intensive game comes out.]
I agree that's the case for most people. But I know a lot of people that still have GeForce 2's and 3's on reasonable systems (1.4+ GHz). Waiting for 4-6 months for them would either seem like an eternity, or ruin the game because of low quality.
In their cases it might be wise to get a new video card, just not THE top of the line. Something like a 9700 would cut it, and probably only cost 200-300 USD.
"Space. It seems to go on and on forever. But then you get to the end and a gorilla starts throwing barrels at you."
-Fry, Futurama