Rig wont power up

I shut down my rig a couple weeks ago and went to bed, the next day when I attempted to power it up it wouldnt turn on. All it would do is flash the led's on my case fans right quick and that was it. Immediately I thought it was my power supply but I wasnt sure how to confirm that so Ive let it sit. Last night I decided to open up the case and do a visual inspection, make sure everything is connected, look for obvious stuff, before I opened it up I figured Id try to power it up again....What it does now is as soon as I turn on the power supply, all of my case fans light up and spin at a low speed, the cpu cooler fan lights up and spins slowly too, the psu fan lights up but doesnt turn on, even the gpu fan spins, all at approx the same slow speed. I can even hear the hd spinning slowly too. Pressing the power button on the case does nothing at all. When I turn the psu off, the case fans flicker and then shut off. When the fans are lit up, its not at full tilt, its maybe 50-75% as bright as they normally are.

Does this sound like a psu problem or something else? My rig is approx 5-6yrs old and I do plan on building a new one regardless if I get this one up and running again bit Id like to get this one going again if possible so I can start prepping for the new rig......plus its killing me not to be able to update my music on my ipod. Any way I can test the psu to see if its the cause, short of buying a new one?

PSU tester:
http://www.amazon.com/24-Pin-Atx-Pow.../dp/B0017WLJ7S

I had this same exact problem 2 days ago. The motherboard lights would power on, and a few fans would spin slightly but nothing would truly power on. I took it in to the local computer repair place for a diagnostics test. My PSU was only outputting power through 3 channels. I had to replace it. I decided to upgrade to a 750w PSU to ensure that wouldn't happen again.

Wow, sounds very similar to whats going on here. I have to buy a new power supply for my upcoming build, that plus the description of your problem and the solution has me pretty optimistic that it is the psu. But I guess even if its not it wont be money wasted cause I was gonna get the new psu for the new build anyway. I hope thats all it is, I gotta get my comp ready for the new build. Make a list of the programs I want/have get rid of the stuff I dont need, etc.