The original m8400f PSU is rated at 380w...will that be enough? If not, I would appreciate suggestions and links to recommended replacements...the board's instruction manual calls for no less than a 500w PSU "for expansion purposes", but I plan on only using the original m8400f components, if possible. Thanks in advance for your help.
You'll have no problems with the original 380w HP power supply to run your system. It's only if you want to add a discrete graphic card that you'd need to install a more powerful PSU. There's even some graphic cards that would be just fine with the 380w such as the ATI HD4670 and others.
*EDIT* if your system has the GeForce 8500GT graphic card installed the 380w is plenty of power for that also.