A couple of things:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817151092
that is better than any of the PSUs posted so far. More A on the 12V rails and cheaper for what you get and is a very good PSU
and he is playing WoW, he doesn't need to spend money on a 5770 or 4890, I max it out on my 3870 with full AA and everything up and am at constant 60fps. I was in VOA 25 man (25 people in the same place at the same time all casting and doing stuff) and still sit constant 60 fps. My friend has a 9800gt that runs it on full no problems aswell, so you could probably actually go for a 9600gt and still get good fps on max settings.
And I would recomend a new HDD, even if it doesn't improve performance in game, which it won't other than when you enter/leave instances, battlegrounds or go to new areas, it will make the entire system run quicker. If you do get a new hard drive though, don't get the 500GB ones posted, you can keep the 1TB one already in there, you only need a small one to put programs that need the performance, the 1TB one can hold everything else like utilities, music, films, files etc
So, a NEW list:
Power Supply:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817151092
Graphics card: Any of these will play it fine on full, depends how much you want to spend:
(lower price = lower performance, the gts 250 is quite a bit better than the 9800gt and just about better than the 2850, but you won't notice the difference in WoW)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814500113
http://www.newegg.com/Product/Product.aspx?Item=N82E16814102824
http://www.newegg.com/Product/Product.aspx?Item=N82E16814261057
Hard Drive:
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136074
If they don't fit in your case, you don't have to spend silly amounts on a case just because it looks good, you can a get a $40 case and it will hold your components fine and keep them cool enough.
Any mATX or ATX or full tower case will fit all of that in, so if you have problems fitting them in, then just have a look for any of those on newegg or elsewhere