It s ram related ,but software could be involved.
Test RAM with Memtest 4.xx for some hours.
1.Disable CnQ and turbo core or whatever power management is for CPU in BIOS
2.Use a SP3 image.If you don t have one slipstream a SP3 in it .
Use XP ISO Builder from some trusted source like softpedia or similar.
SP3 is available on Microsoft website.
3.Use IDE Mode for the SATA controller.
4.Install ,configure install security software firewall and such and imediately update XP to the latest updates.
5.Go back into BIOS re-enable Turbo core and such.
For CNQ to work in XP you will need to find somewhere a specific CnQ version ,it may be available on Softpedia can t remember exactly.One version of this CnQ will be able to dynamically use the CPU clocks properly ,but the Desktop will not be as smooth and snappy as in Windows 7.
That is all.Use Catalyst 13.4 chipset and video drivers from AMD website don t bother with others.
Catalyst 13.4 is the last to support XP.
Chipset drivers are here ,scroll down ->
http://support.amd.com/us/gpudownload/windows/Pages/raid_windows.aspx