Black screen on startup... (barebone system)

[Lasserith]

I just put all the hardware together (easy part) but now i need to install OS/drivers. The problem is whenever I attempt to boot off the windows xp disk (or turn on my computer for that mattter) the monitor doesnt recieve any data and simply remains black. Anything I can do to get it working?
Mobo: ASUS A8N5X
Video: EVGA Geforce 7800 GT
EDIT: Its probably just my powersupply ill have to get a new one...