I see you want to go with an AMD processor. You should check out the benchmarks of the new X4 Phenoms vs the Core 2 Quads from Intel, then make a decision from there. Most people here will tell you to just go Intel, because it's pretty common knowledge that they are faster clock for clock.
For the motherboard, if you don't know anything about Intel, I suggest you do some research on that. Look at P45 chipset based motherboards, as they are relatively cheap, feature rich, and mostly overclock better than Nvidia based motherboards.
For the graphics, save yourself some money, get an ATI 4850, it's much much better price/performance than the GTX260. In fact, it near matches that card in most benchmarks.
PSU: PC Power & Cooling 610w Silencer will be perfect.
RAM: that stuff is fine, use a 64bit OS to make use of all 4GB.