Is this computer upgradable? Lenovo M58p-7484 Desktop E8400 3.0GHz 2GB RAM 160GB HDD?

I am thinking of getting this computer used and upgrading a few things on it so that I can play Starcraft 2 on the best settings such as RAM and Graphics Card but I don’t know a LOT about computers. Is this computer upgradable? Below are the specs: Lenovo ThinkCentre M58p-7484 Desktop E8400 3.0GHz 2GB [...] http://bit.ly/jPgkMf