Vista Recovery is the best way.
I just installed XP and the dual-boot is working fine now.
How? with the following steps;
Note; This is if you install XP after installing Vista.
- Boot from my Vista DVD, perform, "Startup Recovery"
- Restart, and Vista loads.
- Download & Install EasyBCD from here: http://neosmart.net/dl.php?id=1
- Run EasyBCD and goto; "Add/Remove Entries"
- In the version drop-down menu select, Windows XP
- Change the drive letter to one on which XP is installed, rename accordingly.
- Hit, "Add Entry" and then "Save"
Voila, when you restart you will have the two options infront of you, i.e., if you want to boot into XP or Vista.