Maximum PC

I built my first PC a couple years back but haven't kept up with recent technology. My cousin wants to build one and I said I'd help. He's looking for something around $800, there's good wiggle room around this number. I think he really only plays WoW, maybe a couple others but nothing too intensive, other normal teenager stuff: bunch of tabs open at once in a browser, probably a torrent client running in the background, etc. Basically, most important part is running WoW and whatever pretty nicely, but to still handle the other junk within reason, and maybe a little room for upgrade-ability down the road.

Since it's been so long, I'm out of date on sandy/ivy bridge, I've done some reading though, and brushed up a bit but was just hoping for some feed back on my selections, and perhaps some recommendations on thing's I'm off or missing. Most notably, I want to make sure everything I've selected will be compatible -- the LGA 1155 and Z77 aspects etc...

Mobo: GIGABYTE GA-Z77MX-D3H LGA 1155 Intel Z77 HDMI SATA 6Gb/s USB 3.0 Micro ATX - $119.99

CPU: Intel Core i5-3570K Ivy Bridge 3.4GHz (3.8GHz Turbo) LGA 1155 77W Quad-Core - $229.99 >> $15 off

RAM: G.SKILL Ripjaws X Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) - $49.99 >> $10 off ------OR------ 8GB Kit (4GBx2), Ballistix 240-pin DIMM, DDR3 PC3-10600 - $45.99

Hard drive: Western Digital Caviar Black 1 TB SATA III 7200 RPM 64 MB Cache

An optical drive is of no concern.. But my first question is should I consider a graphics card, I selected this mobo for its integrated graphics but will it be sufficient for what my cousin is after? I'd also like some opinions on an adequate power supply, how many watts should I have to support this rig? Recommend a suitable one please.

Thank you for taking the time, you're helping me help a teenager further an interest in IT!