Well its obvious you did not build the PC your self then.
have you applied all the updates to SC2?
is this the only game that runs slow.
if its NOT then i would suggest take it back to where you bought it for diagnosis or atleast call to describe the problem.
I've already applied all the updates to SC2.
I have yet to test out other games but for now I only have SC2 to really test on.
I'm waiting for D3 actually.
I didn't build the PC myself because I'm not really good with the wires.
I'll post a picture up when I get back it's 11.40am at where I'm from so, it might be up by the time you guys wake up.