This is simple: copy the System and System 7.5 Update files (in the System folder) and drag the copies to the desktop (or hold down the option key and drag them to do this in one step.) Double-click on the Part 1 patcher which will ask you to locate the System copy and then produce another copy of called “System” Part 2 will do the same for the Update file. Compress the “System copy” and “System 7.5 Update copy” (StuffIt or Compact Pro recommended), put them somewhere safe and throw the original copies away (the ones actually named “System copy” and “System 7.5 Update copy” that is.) Open the System folder and drag the originals to the trash, then drag the new copies the patch gave you from the desktop into the System folder. Restart your Mac and empty the trash.
If you have any problems (god forbid) or you decide to go back to your original system (again — god forbid), just decompress the backups, rename them "System" and “System 7.5 Update” accordingly and put them in your system folder after moving the patched versions into the trash. Restart your Mac and you’ll be restored to System 7.5.1’s boring startup screen and icons.
