OK, I've done a bit more investigating (and read your post in more detail!! ) and have downloaded the latest AMD southbridge chipset drivers, which you can get from here:
http://support.amd.com/us/gpudownload/windows/Pages/raid_windows.aspx#4 (the supplied link should take you directly to the Windows XP tab; copy and paste into your address bar as this doesn't appear to want to post as a hyperlink)
I assume you're not trying to run a RAID array?
If so, just download the AMD Chipset drivers; you won't need the other two downloads.
1. Run the installer program, and allow it to extract the files to your hard drive (I'm assuming you're not posting from either of the machines you've mentioned above)
2. Then cancel the installer program.
3. By default, I would expect the files to be extracted to C:\AMD\Support.
4. Assuming the above and that you are working with 32-bit Windows XP browse to the following folder which should have been created with the extraction: C:\AMD\Support\13-1_xp32-64_sb\Packages\Drivers\SBDrv\SB7xx\AHCI_svr\XP
5. Copy ALL of those files to a blank, formatted floppy disk.
6. Use this floppy disk in the Windows XP installation.
Hope this helps.