For WoW, it's overkilled. Believe it or not, WoW isn't as intensive as you think. Your computer will do fine for many games at 1080p. I'm guessing this is going to be build for a third party? See if you can opt for for i5-2500k. The i7-2600 doesn't offer any noticeable performance bump over the 2500. It is also possible to get the i3 2100 instead. It's a dual core but it's a beast in term of gaming performance compared to quad cores at higher price point. If they can let you change the motherboard, go for either H61/H67 if you have no plans to overclock. You may safely drop to a 500W power supply. 650W can run 560 ti sli just fine so you're overdoing that too.
Definitely. I used to run WoW on a PCI (not PCIe) GPU, 1.5GB of DDR RAM and some P4 CPU. Granted, it was around 10 FPS, but it still ran. That being said, you could take 1/10th of the performance that build offers and still be fine.