I could get a cheap dual core 939'er a my CPU is slowing my games down when there are 10+ NPCs running around, but for example, in puzzle maps in HL2 DM when everyone is lined up hopping around waiting for a door to open, my FPS can go from 100 to 20 easily. and in crysis on recovery, going into the school and about 50 koreans and 2 tanks spawn and start shooting, my FPS goes from 22 to about 8, unless i turn down the settings. of course, i only have a GB of ram, and i would love to test on 1.5 gb of ram, since it could be a ram issue, as most of the time when any of my games slow down, HDD starts activating. and my PF usage now is always 600 MB plus.
Too bad my mobo now only has 2 ram slots.