Slow Computer

This probably won't help and it may not be your problem but from my experience I did not have any luck with running amd and xp without having problems with booting speed I had an AMD cpu based pc running at 1 ghz which ran fine for years with windows 98 but when I added the xp it took like over 1 minute to boot and that was after a fresh install and after adding a few programs it got even slower while my laptop with an intel cpu at 700nhz is booting at about 40 seconds with other software installed I replaced the pc with a 2.4 ghz cpu and it booted in 20 seconds and now with software installed it's about 1 minute
So if after the clean install it boots in 20 seconds i would say you have a chance and it may be just the programs you are running but if you are booting at 1 minute after a clean install I don't think it's going to get better unless you switch to intell
This is just my opinion and I am sure others will say they have no problems running amd and xp although I am not sure if the actually measured the speed or they probably think it's normal. One guy said oh it's not a problem I just turn on the pc and then go and fix myself a cup of coffee

Hm aside from an overheating CPU, which causes the CPU to be slower because it 'throttles down' so it uses less power as a safety mechanism, there is also another possibility.

High CPU usage whenever you need to access your disk is typically a PIO problem; PIO is an old way to communicate with the harddrive and is only used when DMA (fast Direct Memory Access) did encounter errors. Anyway a PC that uses PIO to read/write to the disk will be very slow and have very high CPU usage, when accessing the disk.

Normally this can be corrected by deleting/removing/uninstalling the IDE/SATA controller from the Device Manager window. After you reboot, it will be found again and it will try to use DMA again instead of slow PIO.