I've been using the same setup for awhile now (Phenom 9650 @ 2.5ghz, 690G mobo, 4gb ddr2, hd3870), and I have not felt the need to upgrade for some time. I rarely game, and the 9650 handles my video encoding tasks just fine.
The last game I really played was Dungeon Siege, and that took me nearly three years to complete the single player campaign. I tend to play a game for a few days, put it away, and then come back to it in a few months when I feel the desire to continue. The only game I have been looking forward to playing is Dragon Age Origins, and I'm not sure if my current setup is up to snuff. I have a 19" monitor at 1440x900.