i think most people get PSU's that are overkill.
I'm running fine off an Antec 500watt...I have a floppy, 3 SATA hard drives (2 in RAID 0), and 1 DVD burner..not to mention my CPU is overclocked 550mhz and my GPU is overclocked a bunch too...and 2 sticks of DDR memory running at 230mhz
I also have 2 120mm fans, a 92mm cpu fan, an 80mm LED fan, and 2 Cold cathode tubes.