It looks like I can drop a q6600 in my system for $180 from the local Microcenter. Doesn't look like I'll have to change anything else. I only use this computer for video encoding and web browsing.
They have a q9450 for $250 and a q9550 for $300. Would have to upgrade the motherboard, probably another $150-$200. Is my ddr2-800 ram(corsair xm2 if it matters) good enough for overclocking one of these 2 cpu's to 3.2, 3.6 etc? If not, add some more $ for new memory.