I want to upgrade the video card to a hd 7770. It's not very expensive, and it should suit my gaming needs. I'm new to computers, and I'm not sure if I'll need to get a new power supply though. Any help would be appreciated.
You'll probably need a new PSU, the stock OEM ones aren't good. The 7770 isn't a bad card, since you found that out yourself don't you think you would be able to come up a build on your own? It'd save you money, you'd have a better system, and you'd come out with much more knowledge.
Yes better quality, and many low quality units won't deliver close to what it says it will. I've seen some say 750w and they'll only do 500w. Also low quality PSU's can blow up and when that happens it can very likely take everything else with it.