How to dual boot Vista and XP (with Vista installed first) -- the step-by-step guide with screenshots
http://apcmag.com/how_to_dual_boot_vista_and_xp_with_vista_installed_first__the_stepbystep_guide.htm
How to dual-boot Vista with XP (with XP installed first) - step-by-step guide with screenshots
http://apcmag.com/how_to_dualboot_vista_with_xp__stepbystep_guide_with_screenshots.htm
*To edit Vista’s boot manager you have to use the command line BCDEDIT utility.
To access BCDEDIT, run the Command Window as an administrator and type in BCDEDIT.
Unfortunately BCDEDIT isn’t an easy tool to come to terms with, especially as it’s purely command line-driven. So, a great tool to use here is EasyBCD by NeoSmart Technologies. EasyBCD offers a GUI frontend to BCDEDIT, and makes life much easier.
Once Vista is installed, call up the browser and navigate to the EasyBCD download page - download, install and launch the application.
To configure the bootloader go to “Configure Boot” – you’ll see the two entries, for XP and Vista. To change the name of Windows XP, just overwrite “Earlier Version of Windows” with “Windows XP” and click Save Settings... (osv)....
http://apcmag.com/how_to_dualboot_vista_with_xp__stepbystep_guide_with_screenshots.htm?page=5*