Come to think of it, I agree. I remember being surprised to see the 100W rating on mine, and doing some quick math on the power demands of the computer. It was all so disappointing.
The PSU is still useable for hobby use as a steady voltage source, but I'm not sure if it would be ok to place back into a computer.
"An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it will also make better soup." - H.L. Mencken