It is my understanding that there is no going back... however you might try performing a System Restore in XP. You may need to re-install it if you have attempted to remove it.
Start--> All Program Files --> Accessories-->System Tools--> System Restore.
Windows XP creates restore points each time you reboot, or install a new application. If you do the COMPLETE install and load SP1 and any other recommended SP's from Microsoft, you shouldn't have problems with FrontPage.
Good Luck