Well, that cpu is a pretty good oc'er. You should be able to get past the normal speed easily. I'm assuming that the cooling is stock, so you shouldn't push it too much, that is, if you want your comp to last you longer than a couple of weeks. You could oc your gpu, but I don't think that the mx4000 would do you much good. The cpu could be pushed though. You could always go for a smaller hd and get a better cooling system and oc from there. Or get a smaller hd and get more ram, because, no offense, the difference from 512mb to 1gb is huge, at least from my experiences...
Macbook Pro and Logitech z5500s. All you really need.