It's not going to be far off Vice City Specs as it's the same engine a year on.
I know they can make developments in a year, but it's pretty similar. Increased draw distance and texutres, so I'm guessing that a ~£70 video card, and 512mb ram will be great for this game. More than enough.
Your rig should run it fine though Dray. As I'm sure VC runs fine on it also.