I would save a few bucks by parting together stuff that will net me a big OC thats close to much higher priced merchandise. A midrange or even budget C2D will perform right up there with the more expensive models. This system i built recently for a friend proves that if you want to hit an easy 3-3.2ghz on air you can hardly justify spending anything more;
Video, Perfect UT3 Eye Candy:
8800GT
Memory, run 1:1 and EASY CL4 4-4-15 timings
OCZ DDR2-800 2x2gb
CPU, easy stock cooling 3ghz
E4500
Get a cnps9500 or better cooler and bump the vcore on the chip up one or two increments and your looking at 3.2ghz
For example, i have the allendale E4400 (130$ when i bought it) 2mbCache CPU in my HTPC. Using slightly better ram (corsair XMS PC-8500), P5B-VM motherboard, power-on 24.7 at 3.2ghz, on my current dfi lanparty board, i got that little bugger to 3.5ghz orthos stable... tell me thats not an awesome return on such a minimal investment..
If your going extreme and absolutely MUST drop a lot of money on a cpu, theres absolutely NO reason to get anything other than a hand picked E8400 from tankguys, who should be getting more in soon.... so they say. And if you even want a quad core to come close to performing like a decent C2D then again, i'd go with tankguys hand picked G0 or B3 stepping Q6600- but by the time at laeast half of the software you use can actually take advantage of 4 cores, how great is it going to be ? 289 bucks isnt a HUGE investment.