I have a Gateway ID79C with an intel i7-720QM processor and an ATI Mobility Radeon HD 5650 1 GB video card. I cant play starcraft 2 on max settings with this video card so I want to upgrade it.
I know it will probably consist of taking everything apart to install a new card but I am comfortable with that. I am just wondering if there is any way to know if the video card in my laptop can even be upgraded, and if so, which cards could I upgrade to?
I imagine the Radeon HD 5870 or a similar Radeon HD card would be compatible ... but I have no idea.

Well, in most cases of laptop computers. The video cards are integrated within it.
So there is no possible way that you could upgrade your video card. If you want you could try Game booster software. It worked great in my Rig.