Well wehn you install Vista, be sure not to format the drive as the XP boot system files are now on the Raptor. Come to think of it, Vista will probably wrap those boot system files into a folder called Windows.old even if you don't format and you will lose your boot to XP.
This is what I was hoping to get you to avoid, but you can now either backup the files ntldr, NTDETECT.COM and boot.ini so that you can easily copy them to the Vista drive after you install Vista or you can change your boot HDD priority so that the XP drive is your system drive and reinstall XP and then install Vista.

