Check out the P5Q Deluxe, the ones that say 3 in it have support for DDR3 only...
Q6600 is a good choice, it can go up to 3.8ghz on a good Air Cooler and some good overclocking skills
Go with HD 4870 Crossfire or 1 9800GX2 or 1 HD 4870X2 (this will be a true Dual-Core GPU unlike the rest out because it isn't Crossfire on one PCB like the rest out right now)
You really don't need a Quad-SLI or Quad-Crossfire unless you run at like 2560x1600
For 2k I'd get something along the lines of this:
Asus P5Q Deluxe
Q6600
HD 4870x2 or 4870 Crossfire Mode
640gb WD Drive
4gb of G-Skill DDR2 800 or that Patriot 2gb Viper
NZXT Tempest (surgevel sells these really cheaply here)
Corsair 650tx
Since you have the money to spare you could also consider a sound card or some sound system with a good Headphones