CPU for new build need advice

I'm looking to build a new comp for some mid level gaming mainly counterstrike source. I have most of the other components of what I want worked out, except a processor. I'm pretty sure i don't need a quad core so I've been looking at the intel E6600 or the newer E6750. Also been considering the AMD 64x2 6000+ which has slightly lower performance but is $50 cheaper right now. Not quite sure what to do or get, can anyone add some input?

To go with it I plan on:
evga GeForce 8800gts 320mb
2 gigs of mem
dvd burner
good sound card
WD HD possibly raptor
big power supply
MB once i choose a processor

Mainly I'm looking to keep the price down so I dont wanna spend over $225 so I dont really want to step up to the 6850. For motherboards i was looking at the ASUS P5N-E SLI LGA 775 NVIDIA nForce 650i SLI ATX or something similar to that maybe a step down because i dont plan and doing any dual graphics. I'll stick with the asus because i've had good experiences with them.