Hard drive installation issues

hi, my old hard drive crapped out so i went out and bought a WD 500g Sata hard drive today and brought it home, unhooked my old one mounted the new one and hooked everything up put the case back on to begin installing windows onto it...when i booted it up everything powers up and all fans start runnin including the leds in the fan but it runs for about 4.5 secs and then the entire machine shuts down, no monitor activity or anything jsut 4.5 secs to boot everything up and then jsut silence im completly lost as to wat might be wrong or what to try any and all help would be appreciated.
Josh