Well, that last post didn't stay current very long - I've just had to replace the home-built AMD Athlon 1100 after a series of attempts to upgrade the processor to an AMD XP1800.
It's my own fault - I did a bit of reading up online and realised that a certain AMD chip found on eBay would work on my motherboard, so I bid for it. When it arrived, I was too impatient, and plunged straight in on the install.
I don't know what I did; I don't know if the processor was faulty, or if I knocked something on the motherboard, or whatever, but when I connected the CPU Fan to the motherboard, nothing happened, apart from BIOS screaming at me that the CPUFAN IS NOT FUNCTIONING.
The fan works on one of the other power blocks, but that doesn't trigger the CPUFAN sensor. Luckily, I'm the sort of person who takes in old PC's 'just in case' and so I tried another motherbord - with the same result. OK, let's put the original CPU back. Nope, same problem. Eventually, I got a third motherboard working with a third CPU I hadn't realised I had (a Duron), but this had a diferent set of problems - it kept generating errors on boot, and no amount of checking the plugs, repairing and, eventually, reinstalling XP, etc. could resolve the problem.
I gave up, went online and found a nice EpoX mATX motherboard with a Celeron 2ghz and 512mb ram. It arrived the next day and works fine! A bonus is the 4 USB 2.0 ports and the Network port built in, thus freeing up the PCI slots and speeding up my USB device connections!
So, on the minus side - I've trashed three motherboards and possibly three AMD CPU's; On the plus side, I've got a much faster CPU, and a little bit more upgradability. And I've done an XP reinstall, which means a much faster boot and shutdown.
Next step - upgrade the RAM and graphics (courtesy of CEX.co.uk, it's going up to 1Gb RAM and a 128Mb NVidia graphics card - it's currently using 32mb of system memory for graphics handling, which is not good for the sort of stuff I do on it.