Upgrade options for ASUS U31SD-DH31

Well, as the title says, I'm getting the laptop above. It's a stock model, so it'll be coming with the the nvidia geforce GT 520m, which I know is a pretty low end card. I don't know much about laptop concerns with upgrading so I want to know what I can and can't do and what my limitations are. Am I limited with power consumption rates? Will heat generation be a concern? I know its only a 13.3 inch screen, and I have a dedicated rig for gaming, but I thought it'd be nice to be able to play games like Skyrim or MW3 at a decent framerate.