What's affordable? I'd get a sapphire 5770 vapor x or sapphire 5750 vapor x
I honestly wouldn't suggest anything until Captaain Planet comes through with more details about his/her system. For all we know, he/she may have a super old PC that doesn't have an AGP or PCI-E slot. Or perhaps this system uses a slimline design. Compatibility questions are to be dealt with first before making any suggestions.
The only real problem I had with the Cyberpower was the power supply is 500w, which seemed kinda weak to me.
Sure you read that right? Based on the specs, that system comes with a 700 Watter. While it's probably one of their cheaper end units, it should still be enough for a GTS 250. Should replace it eventually though with something more quality, but it should be fine for some time. This is one of the crappier things about Ibuypower's and CyberpowerPC's off the shelf systems...hardware is great for the price, but they always seem to use lower than average PSUs in them.
I just cleaned a 1 and a half inch layer of dust off of pretty much everywhere from the inside of my computer and I swear I gained 4-10 fps in Mass Effect. Is that normal or did my PC sneak some of my steroids?
Ravin
Cleaning out your PC of dust once or twice a year is good practice. Depending on your environment, you may even need to do it more often. But anyways, 1.5" of dust is exaggeratively a lot. It can certainly affect GPU performance though. Too much dust can cause overheating on any component, especially GPU fans. You should probably get to cleaning that out too if you haven't.