I don't know much about hardware. I was planning on buying this, but I just learned that it's PSU can't handle strong Graphics Cards available to me. The Slimline has a 220W PSU, Can I change it for a stronger one later on? Or does it have some sort of slimmer, smaller PSU since its part of the "Slimline"? Can I use any decent powered PSU or does it need to be some special kind?