First Gaming Computer Help

[BulletReign]

My sister is preparing for her first gaming computer! She plans on buying all the components and assembling the machine herself. She plans on using the computer for games like WoW and Skyrim. Her approximate budget is $800 and should NEVER exceed $1000. Here are my suggestions for her build, but since I am an amateur I thought I'd ask you what you think.

Processor: I suggested an AMD processor considering the budget but since I personally prefer Intel I have no experience in choosing which processor to use.

Graphics: Nvidia GeForce 560 Ti or AMD Radeon HD 6870. I prefer Nvidia but since I know very little am unsure whether it would be compatible with the other AMD components.

PSU: Cosair 650w. She suggested a SeaSonic 620w but I don't like that idea :P

HDD: I suggested a 500gb HDD. We have a WD Caviar Black in mind.

Audio: I suggested onboard sound since it doesn't matter too much to her and she is on a budget.

Motherboard: No flipping idea. Whatever you guys think would be best for a low end gaming rig. Remember it should be able to run WoW smoothly and Skyrim (Even if we have to push the budget a bit she REALLY wants Skyrim)

So tell me, what should she buy?

EDIT: Cases! She is debating between NZXT Phantom 410 and CoolerMaster Storm Scout. Leaning to CoolerMaster.