Hehe, I have, or should I say, used to have a PC running on an Athlon Thunderbird 1.2 too.
Nice fast system to tell the truth... never caused me much trouble. Until that is, it decided to just conk out on me for some reason.
Anyway, I took the fan off at one point, and looked at the temps. They steadily rose while idling until it reacheed about 80 degrees C, which is when I placed the fan back on again...QUICKLY!
What is a 1.9GHZ brisbane when its at home?