Power supply: Probably, but I can't say for sure, as I don't know much about your case's dimensions.
Graphics card: Decent card, but given that you already have ATI drivers and are concerned about power consumption, have you considered the HD 4770 or maybe even the HD 4670? It performs at a similar level and consumes less power.
Thanks for the advice. I actually had not thought about ATI at all(mainly because im completely unfamiliar with their naming system, lol), but now that you mention it, it probably is not a bad way to go. Seems like it would save a few dollars as well.
As far as dimensions, the case itself is fairly big (dont have the exact numbers) and it looks like a very standard fit, so I don't think i'll have any problems there.