I have been so into building my own PC that I am not seeing the forest for the trees. I put together an asus barebones with amd 64x2processor with 250gb hard drive and 2 gb memory, dvd burner. When I plug it in, the light on the mobo is on but the power supply does not turn on. I know this is a simple solution, but I can't see it. Any help would be appreciated.

I don't have an answer to your question. But, I think that your question is important. By my posting a response to it, it will get moved more towards the top of the list of questions to be answered. Hopefully, someone who is knowledgeable about what you ask will come along to answer it.

Check if you plugged the "PWR ON" cable into the correct pins on the motherboard. This cable is part of the computer case, along with the "reset SW", "IDE LED", "SPKR", etc. leads.