Your opinions... Computer won't start

[Soup Clock]

My desktop has died and I'm going to be replacing the parts myself.  It is a Dell Dimension 9100, pretty old, but it's lasted 5 years and I'm going to try to get some more life out of it and back up many files that I forgot to before building a new one.  What happens is, whenever I try to power the thing, the light on the power button blinks orange once and does nothing afterwards.  If I hold it down it will blink orange once every 3 seconds or so, but still nothing will happen.  I originally thought that this would be a problem with the psu, but after doing research and finding a post of someone with a similar problem, I believe that it may possibly be the mother board. (http://www.techsupportforum.com/hardware-support/ram-power-supply-support/189996-solved-dell-dimension-9100-power-supply-problem.html very close if not exact same problem)

Just wondering if any of you have dealt with/heard about similar problems and get your suggestions before rolling off of one answer source.  Also, any psu/motherboard suggestions would be appreciated.

[pop-tart]

It's likely the motherboard... or may possibly be a short somewhere.
 
Have you had the power supply tested?

[Soup Clock]

It's likely the motherboard... or may possibly be a short somewhere.
 
Have you had the power supply tested?

Nah, I haven't done that yet.  I was thinking about buying a tester for this and future projects I may have.