Yeah all that crap should work if you install it correctly. However, to run the best games on high-ish settings, that P4 is not great. You can run CS:S, fine, maybe Oblivion, but definitely NOT Crysis or any of those cool games.
Also, don't be surprised if that PSU lasts like three months. It is pretty crappy quality. - Misread the brand, the FSP is quite good actually. Might want to get some splitters/extenders for the wires though.
But I like the choice of the GPU though.
Oh and lastly, you will need 2 gigs of ram for a lot of games. It seems like overkill, but you will definitely appreciate the speed increase.