I have an AOpen HX08 with it's ATX 2.03 300w AMD Approved Power Supply and I'm quite happy with it, and I've had no problems running all my devices off of it,
1.133 Ghz Athlon,
GeForce 2 GTS,
Two IBM 75GXP 7200RPM HDDs,
Pioneer 16x DVDROM,
HP 8x/4x CD-RW,
And of course, the motherboard, the PCI devices, and a couple of extra fans.