Install XP. Use the Vista DVD to get the Vista Menu back. Google for EasyBCD and add a XP entry to the Vista boot loader and mover over the NTLDR, NTDETECT and boot.ini files to the Vista partition.
If you want real info go to NeoSmart.net and ask in their forums. They will have your answers.
Read thru their wiki.
Windows XP - EasyBCD - NeoSmart Technologies Wiki