Alright, I just tried it...
I have a new Dell 8200 with XP Home OEM installed, and downloaded/installed the SP1.
Uninstalled StyleXP, rebooted, ran the patchxp and rebooted....
On bootup, I got the 'unable to load explorer.exe because of missing uxtheme.dll file' etc....
I pressed Cntrl-Atl-Del and the Processes tab. Clicked 'File', 'New Task', and used that Windows Explorer to find the andyp Patchxp.exe and ran the uninstall - then rebooted again - now I'm back to where I began....