I have an older Dimension 4700 that had XP loaded.  I used the Vista DVD to upgrade and seemed to work ok, however very S-l-o-w...   So, I tried to go back to XP using the CTRL-F11 function to restore the machine to factory status.  This did not work, so I loaded XP SP2 from a Disc.  I believe I still have the factory restore image on a hidden area on the drive.

Long story short...  "How do I start the execution of the Factory Restore when CTRL+F11 doesn't work"?  I'm running WIN XP SP3 now.