Help, my comp is dying or dead

[glatt]

Wow, thanks for that informative answer.

One more question, which may sound kind of dumb after all the information you just provided, but the fan in my 2 year old Dell at home makes a fluctuating noise. When I'm doing something really CPU intensive it makes a lot of noise and when I'm just typing in a reply box in the Cellar, it makes a sort of oscillating noise. Sometimes louder, sometimes softer. The PC seems perfectly fine otherwise. This noise isn't a screech like bearings failing, it's maybe just the fan speeding up or slowing down. Is that in itself a signal that the power supply may be failing? If it's failing, I'm going to be glad that you posted what you just did, so I can get a decent replacement.

P.S. I have a multimeter that I use for household electrical work, but have never used on electronics.