So I posted a thread asking what was wrong with my computer. Seems like the symptoms point to a murdered graphics card and now I need help finding an optimal replacement. My former graphics card was a EVGA 8800GT 512MB SC Edition and will be sorely missed. First I want to go with a manufacturer with a lifetime warranty which I had the opportunity of having with my 8800GT but my 17 year old self at the time was too stupid to register. The graphics heavy applications I use are playing HD movies and StarCraft II. With some searching around I've already got these in mind:
I'm a poor college student so I had to make a strict budget. If I didn't need my computer so bad I'd wait till next month to get something around that price but my grades are dependent on getting this computer up and running.
Get the fastest that you can afford, which is easily the 6770 of the cards you listed. I'm not sure it'd max SC2 with a stock Q6600 (and I don't know your resolution), but it will play it better than the 8800GT, to be sure.