Well, since I posted this I have ripped out all the guts, threw them on an antistatic bag, and hooked up just what I need. That is, 1 stick of ram, cpu, PSU, and video card
I double checked all the plugins for power switch, reset, etc. I only have the power switch hooked up.
I took the PSU out of the P4 box and hooked it up to an AMD machine, and it powered on, however the AMD machine doesn't make use of the extra plug that is on a P4 PSU (can't remember what it was exactly). So it COULD still be a bad PSU, but it is unlikely.
I've tried multiple switches on my board now, and it still does not power on, so I'm thinking the board may just be bad.
Anything else I've missed?