Okay so im looking to upgrade my PC a little bit. Its a Dell i got earlier this year because my laptop fried on me and really needed something quick, so i found one online, wasnt a bad deal, i think i ended up paying like, 500 for it with the whole set up. monitor, speakers, keyboard mouse etc etc.

Its an Inspiron 620 with an i5 processor

300Watt Power Supply

6gb DDR3

Integrated graphics card.

Standard Sized Tower, not the mini tower or slim tower, this is a regular sized tower. About 18" tall, 6-7" wide, about 20-23" deep.

1 PCI Express slot.

It can run Fallout 3 on High without too much lagg, but it cant run Skyrim on any settings. So im looking to upgrade the Power Supply as i just found a 550w power supply at best buy for 39 bucks, in order to run a more powerful Graphics card than the Radeon 6670. I was hoping someone could give me some suggestions, or reccommendations. Ive been looking around but its been at least 10 years since i went looking for computer hardware and i really just dont know what supposed to be looking for. I know i want DDR5 on the card, probably 2 gigs of it. Any help would be much appreciated, and if you need more information about the PC, ill try and get it posted. Thanks guys!