If you want to overclock, I wouldn't recommend corsair...especially not value RAM.
OCZ Platinum Rev 2
Patriot XBL series
G.Skill and OCZ right now are basically the two best OC'ing modules you can get....at around $300 for 1gb I'd expect nothing less
Overall the X800XL and 6800GT are really close in performance, but the price is the main factor here. Damn near $100 cheaper for the X800XL so I'd say that's the way to go.
Other than that frontsides suggestions of the ABit board is good for OC'ing, also DFI lanparty boards are really good.
3000+ or 3200+ either or will give you good OC'ing potential, I'd suggest winchester core. They run cooler and have a tendency to OC a little better, but with good cooling you could get a nice OC on the newcastle as well.
Snide remarks like that aren't needed dude. Granted it's in the OC'ing section, but still, there is no reason for 'biotch' at all.