ERM, seeing as how you kept your same PSU over your upgrade, I would say that is a major problem, though I would expect that most of your devices that use 12V (HDs, optical drives) would not even run at all on that sort of power. Get a PSU from someone and test it out, but make usre that it is a reasonably good quality on that is no less than 450 watts. Wouldn't want you cooking your video card
You should try to get a multimeter to measure the power, if you need help with finding out how to measure it, give me a shout on the forums, aim or msn.