You're more than welcome. Good luck with your build.
Oh by the way, a quality 520W PSU such as the Seasonic 520W would cover up to a 200W or so TDP graphics card, one that comes to my mind is the $500 GTX 680 for literally maxing out and maybe some more on graphically intensive games like BF3 at 1980 x 1080 resolution (like a 1080p full HD monitor).
So, dream big, lol, I am sure you don't have an unlimited budget as a student, but I recommend you Google for GPU benchmarks for games that you play just so that you can see what you can expect with the Radeon 6870. Depending on what you see, you might be motivated to spend another 50 bucks or maybe 50 dollars less on the grpahics. Make sure to check the "resolution" of the benchmark though. The lower the resolution you play the game at, the less the required GPU strength is for producing the same frame rates at the same qualtiy settings.
If you decide to go with something other than a Radeon 6870, please come back here and ask to make sure that your PSU can cover the card. The price does not *always* correlate with the power consumption of the grpahics card because newer lines of cards are more power efficient / some of the older generation cards consume a lot for what they do and can be cheap because they don't do much for what they consume and have older technologies, if that makes sense.
Lastly, this computer case can accomodate up to 11" graphics length. So, that's another thing you wanna make sure before buying the grpahics. Prehaps like 98% of the graphics cards on the market are 11" or shorter. [The Radeon you posted would be fine]
i7-2600k @4.5GHz, Scythe Mugen 2 Rev. B, 8GB DDR3 1600, GIGABYTE Z68XP-UD3P, GeForce 9500GT, PC P&C 610W, Plextor M3 128GB, Hitachi GST 7K3000 x2 & WD Black, ASUS DVD & LG Blu-ray Burners, Win7 Pro x64, CM 932 Case.
HTPC + Media Server: http://www.eggxpert.com/forums/permalink/5855/836221/ShowThread.aspx#836221