Hmmm, Im not an expert but the same thing happened to me and it turned out my powersupply went bad and I ahd to replace it (if this is the case dont worry they run less than $50), or if that isnt the case you could always pull your harddrive off and use it as a slave and get info off of it.
Please describe exactly what happens like does it bootup like normal and then crash or when you hit the power button does it not come at all, any errors, anything like that? If you hit the power button and your pc doesnt boot up then its most likely your power supply.
hope this helps
Edited by shifty2991, 23 October 2006 - 06:44 PM.