Upgrading my brother's comp - need advice

My brother has finally given up and gotten Steam, haha (it was the new Monkey Island games that did it). He called me last night and told me he was having a bit of trouble with slowdown in one of the games he's downloaded, and I figure (though I haven't gotten the chance to go take a look at his computer yet) that it's probably a graphics card issue, I don't really know anything about what he's got under the hood except that he got it from Fry's as an HP premade, probably about a year ago. I can't be 100% it's the graphics card, but I know my brother- he probably went for more of a multimedia package than a gaming machine.

I told him as a temporary measure to go into the video options and turn off anything like water effects and AA until I was able to take a good look at his specs.

Anyone have any recommendations on a graphics card to suggest to someone who isn't a hardcore hardcore gamer but still wants some decent performance? Will update this topic as I learn more about his rig.

It just occurred to me that he might not have the latest drivers for his graphics card too: I'll have to ask him about that.

I would recommend a radeon 4670 which is cheap, does not require psu upgrade and is a very decent performer.. if you're lucky and find a radeon 4770, that's a no brainer

I say a 4670. If it's an HP prebuilt then it probably won't have too much reserve power on the PSU so getting something more powerful will require a better PSU as well.