Well, I replaced the CPU fan. Then I brought the machine back, and the overheating alarm kept going off! I took the machine back to replace the tower fan. Then I went home to settle back to some glasses of wine. As I was sitting there drinking wine, the overheating alarm in the computer went off again. Except there was no computer, so there was no overheating alarm to go off!
I looked around. My APC Uninterruptible Power Supply (UPS) was sounding the alarm. When your UPS starts to die, it makes a beep beep beep beep sound that sounds like the overheating alarm in the computer. We now think that the problem was the UPS going off all along and that the CPU fan didn’t even need replacing.
I will disconnect the computer from the UPS soon and see if the problem goes away. In the meantime, I have moved the fan away from the computer and I am no longer blowing cool air into the computer.
On the upside, I have a new CPU fan (which I more or less needed anyway as the old one was badly grunged out), and I am going to get a new 1 GB memory stick. I am running off a mere 512 MB right now, but Windows 2000 runs quite smoothly on that, believe me. Much better than Windows XP, which I think is a much inferior OS. When I get the new stick, I will have 1.5 GB RAM, which should be very cool! Things were getting a bit constricted on 1 GB.
Thanks for all your help!