I'm rating your parts' compound wattage at 430w at most. So I say it's safe enough - but don't forget hooking up other stuff needs more power as well, such as sound cards, external hard drives, etc... So in all honesty I think 600w will give you a stable system with some leeway, and you can upgrade later to 750w when you get your new HD. I would say it's fine. But wait for more opinions.
Well I was looking at power supplies and found one not too expensive, well built, and HUGE wattage. I'm making my credit card company very happy with this build.. have replaced alot more than I was planning to.