PiKapp is spot on, it's the power supply (+1 to his/her rep). Frank, if you don't know what you're doing with the innards of a PC, ask your computer geek friend(s) to replace the power supply with one that will handle the power requirements for your system.
Note that it's possible if the power supply blew it *might* have taken out part of the motherboard, ram pr proc as well. However, the good news is that every time i've had a blown P/S on one of my personal systems, only the P/S needed to be replaced.
Good luck.