This is based on what I've heard here and Tom's Low Cost System.
All prices are from newegg. The cpu and mobo are cheaper from mwave but after shipping I would only save 5 bucks so I'd rather get it all from egg.
CPU - Core 2 Duo 6550 2.33GHz ($175.99)
Mobo - Gibabyte P35 DS3L ($99.99)
Video - 8800GTS (320MB) ($279.99)
Case - Cooler Master RC -690 (59.99)
PSU - Fortron Source 450W ($57.99)
Memory - G.Skill 2GB DDR2 800 ($69.99)
HDD - Seagate Barracuda 7200 320MB ($79.99)
Optical - Sony NEC Optiarc OEM ($32.99)
OS - Windows XP Pro ($0)
Total - $891.05 including shipping
For the PSU I get a total usage of 435W from eXtreme Outer Vision - eXtreme tools for computer enthusiasts
And for $18.16 more (including shipping) I could get the E6750 2.66GHz from mwave by buying that and the mobo from them.