Actually it is a matter of a few minutes to make the change.
Open Explorer.exe in ResourceHacker, edit stringtables 37 (for xp-look) and 38 (for classic look), hit compile script, save as Explorer1.exe to the Windows directory.
Change the registry value for Shell to Explorer1.exe at
HKEY_LOCAL_MACHINE\ SOFTWARE\ Microsoft\ Windows NT\ CurrentVersion\ Winlogon
Open Explorer.exe in ResourceHacker, edit stringtables 37 (for xp-look) and 38 (for classic look), save the altered Explorer.exe as Explorer1.exe. End the Explorer.exe process in Task Manager, click the "Applications" tab, click "New Task", search for Explorer.exe and rename it to Explorer2.exe, rename Explorer1.exe to Explorer.exe and run this new Explorer.exe as a New Task.
Marginally quicker than a re-boot I think, but then my re-boots take a lifetime
Edit: Sorry this only works if you have removed/renamed the backup copy of Explorer.exe