Gateway SX2800-07 for gaming? Upgrades?

I am looking to get an inexpensive desktop to run games on (SWTOR, Portal 2, nothing crazy) instead of my laptop. As a college student, I have a very small budget and not enough time (nor experience) to build my own PC. I saw a Gateway SX2800-07 on sale on Craigslist (http://bloomington.craigslist.org/sys/2644789793.html) and was wondering how this system will fare for gaming? Alternatively, what would I need to upgrade in the desktop?

Please keep in mind, I do not need a computer that will blow me away. I do not need to biggest and best computer out there, just the best for fairly simple games like SWTOR or Portal 2 on decent settings.

Looking at the same issue. Its only 220 watt p/s. Not sure what it draws stock but its going to be tight. I think I'm going with a hd6670.
I have word that it works with the 5570 and the 4650 which I think is s imilar power but older.
also looking at the 6570 .
If any one has good info on what card around these series would take less max power by 10 or 20 watts over the others please let me know. Its goona be close.
Another Idea i had was just put a std p supp outside the case and run it that way or put he whole thing in a new case. It looks like it would mount up fine.