It should; I've got an Athlon XP 2500+ (Which runs slower than that) and a Radeon 9600 XT (which might be exactly the same card), and I run it with everything turned up and still get zero lag.

Memory shouldn't be an issue, since the recommended RAM is 256 MB, which is half of what he's got. More is better, though.

(Oh, and please don't ask me to take out some of my RAM to double-check; I'm running a legit copy of XPee Pro, and taking my RAM out and putting it back in would trip Product Activation)

I think once you get over double the game's requirement, it just doesn't matter anymore.