600 watts.
I will be running:
Hard Drive
ATI 4870
2gb Ram
P35C-DS3R
E6850
Maybe a DVD drive.
The reason i am so doubtfull about failing PSU's is because my dads job is to design and build servers, he brings home specification and pricing sheets. He buy's skimpy, cheep, and what you would say is certainly unadequate PSU's for the servers and has no problems. He used to to buy good ones, he got told off for spending too much, so he cut down on the pricing of PSU's 5 years ago and hasn't had any problems since.