I run an Intel 5300 2.6GHz, 4GB DDR2 RAM, and a 4850 1GB edition, and I'm able to run the game on maxed settings at 1280x1050, albeit not at the best of framerates (15 at worst, and 46 at best). Still, It's a good enough experience that even without sound on, I get terrified playing with just KB and M, which is more than I could say for the 360 version with 2.1 Surround gaming chair and the good-ol' vibrating controller. With said gaming chair, this is practically a slice of the most heavenly realm of hell.

Anyway, that's a computer you can put together yourself, bought in parts at TigerDirect, for less that $500 before tacking on the OS, which turned out to be Windows 7 RC for me: therefore free.

Good luck!

I can't afford a 360 controller for my PC (I had to custom-build it using bought-direct parts, but then again, I now have a $500 monster rig).

However, the KB+M controls on Dead Space, for me, are excellent.

I also recognize why the mouse sensitivity, at maximum, seems so sluggish. I'll explain:

1) the devs of this game want you to feel claustrophobic, and totally immersed in being the character. They did something I hope to see in the future from all game devs: they made the gameplay fit into the atmosphere they wanted to create, which was a combination of tensity, dread, disgust, and vulnerability. You're not used to the subtle differences in the controls, but you can still do it. For some reason, those extra brain cells that are required to do the same things in other games make this one much more terrifying. You can't turn around quickly because it makes you feel too much like you're pushing a button to move, rather than being the character, and moving with the character. It's similar to jazz musicians who intentionally falter at moments of emotional stress or intensity during jams. It adds an extra twist to really draw you into the heart and soul. That's reason one.

2) In purely gameplay-based terms, the mouse is only slow when you're aiming. They don't want you to aim all the time. They want you to put down the gun, look around, run, then be able to start shooting again once you're ready to line up a shot. You're not a soldier, nor a S.P.E.I.A.L.I.S.T. in some random elite organization of training-ness. You're an engineer, and a rather whipped one at that. This isn't a twitch shooter. This is a shudder shooter. The difference has now been made, and may it continue to develop into separate genres of shooter.

3) They're probably expecting the average gamer to have one of those super-expensive 1-zillion DPI 1337 Mice of over-the-top-ness if they intend to play Dead Space like a twitcher. I think they're right to believe that.

Anyway, just my opinion.