@Roffen
The following is from the USP4 Readme posted by harkaz in his cloud folder:
---------------------------------
"Removing Service Pack 4
You can use Add or Remove Programs to remove SP4 and restore your computer to its previous state. Uninstallation is possible only if you have chosen to archive system files during Windows XP SP4 setup.
To remove Service Pack 4 by using Add or Remove Programs
Click Start, and then click Control Panel.
Click Add or Remove Programs, click Windows XP Service Pack 4, and then click Remove.
Follow the instructions that appear on your screen.
Important
If you started but then canceled Windows XP SP4 removal wizard you MUST check if the %systemroot%\system32\catroot2tmp folder exists. If it does, stop Cryptographic Services and move all its contents to the %systemroot%\system32\catroot2 folder (replace existing files). Finally, restart Cryptographic Services. If the folder is not there, restart your computer IMMEDIATELY.
If you choose to remove SP4, a dialog box displays a list of the programs that you installed after you installed SP4. If you continue with the removal, these programs might not work correctly.
After removing SP4, you will be unable to access any exFAT formatted drives unless you had installed the required update before installing Windows XP SP4."
---------------------------------
I would love to hear why you would want to remove the service pack. I would also caution you that your PC will not be as secure with the service pack removed. Additionally, depending what tweaks you have done (pre and post SP4 installation), you might have some unexpected/undesired results.
Regards,
®