Vista - Need advice on setting up a dual boot vista / xp?

I have just about finished setting up, tweaking, etc. a new Vista pc.
I would like to ( for a short time ) set it up so that my xp
installation is still available should I run into any unforseen
software issues.
The XP installation is on another pc so I can take the drive out of it
( all drives are SATA if that matters) and add it to my new one. I
have no experience at all with dual booting so I'm not sure where to
go from here.
Any advice would be appreciated.
Thanks
Gary

>The XP installation is on another pc so I can take the drive out of itIf the other liscence of XP is OEM you cannot do that according to EULA or
you are pirating.
Even if its retail and its ok with the EULA, many things might mess this
up.. since xp might just give you a blue screen or struggle trying to load
onto the new hardware.. It might work but it might not.
You will need to activate again....

anyway... if you have xp on a second disk you can boot the vista dvd, and do
a repair of the bootloader so it will detect XP and add it into the
bootloader.