I've been looking at some systems and it seems like people that have old CPUs (AthlonXP, old 939s) game fairly well as long as they are running a good video card like a Geforce 7800+ or a X1800 or X1900 (which are ultra cheap now). If you're looking at a bare bones bang-for-the-buck upgrade it seems like you're better off just throwing a newer GPU in an old box then upgrading the entire thing, especially if you're looking at *current* gaming and not theoretical games in the future that demand multi cores. I realize an old CPU will hold back an 8800gtx or something and would be necessary for ultra high resolution gaming, but what about something more modest?