I used Acronis Disk Director Suite - the wizard made it really easy.

yeah acronis or paragon paragon partion manager or you can go to disk
managment in vista,, to create a partition ..if using acronis make sure
you create a partion for a dual boot os..if your not going to use 2 os.
just create a partion for data,, the wizard in acronis will give you 3
types of parttion you want to create. and will explain what each
partition you create is for. also do a goole,,, your find lots of info
on how to create a partition. also 2 gig,, you have plenty of ram xp
uses less than vista anyway..and if your dual booting your only be using
one os at a time.

Do you have any driver problems presently?

Make sure the XP drivers are available.  Booting into XP without using a
third party boot manager to hide the Vista partition will wipe out your
shadow copies and restore points.