from what i know, the power supply can go higher w/out a problem. it just gives you more juice if you start plugging extra things in, like multiple drives. my computer started off with a 300 watt power supply, then i got a new case with a 420 watt power supply, and after a while added another hard drive and a DVD rom drive as well. the case was cheap too, under $40 shipped with 1 year warranty.