Hi Ron,

Actually William Wilson did post the tutorial see this URL
http://www.syschat.com/how-dual-boot...ista-1818.html
However,that may not be what you wanted/expected,since it deals with adding Vista to XP.

I think the following info is what you're after:
VistaBootPRO - Go PRO with Windows Vista and VistaBootPRO
and also this post (3rd post by Omego2K) in this thread:
dual boot XP and Vista where you install XP after Vista

Good luck,

Pete.
PS if you want more links,just do a search for "install XP after Vista" or similar.