PC on its last legs

The other night I thought I'd settle for sure if I could remove the loudly whining fan on my PII cpu, and thus remove a source of pain. I found that the fan is integral to the CPU housing, so no luck. When I put everything back together and switched on, I found that there was no mouse pointer in Windows 2000. My keyboard wasn't working, either, although the lights had flashed appropriately when the PC booted up, and hitting a key helped Windows start up. In fact Windows was registering every single piece of hardware from the floppy disc controller on through the serial ports, as if they were all new. Then it would just sit there. I tried a Knoppix boot disc, and it couldn't see the keyboard. In fact the BIOS didn't respond to the DEL key for setup. The mouse is serial, and the keyboard PS/2. Not connected, so the failure of one shouldn't affect the other, I thought. However, a day later, I unplugged everything and re-plugged, and found that the keyboard was plugged into the second PS/2 port. I moved it back to the one next to it, and suddenly everything works as well as usual, including the mouse. Windows can now remember all the hardware. Lesson: must replace this PC SOON.