From what I read when I decided to make a dual boot with Windows XP Home and Vista Ultimae 64; I had to install XP first, then Vista. Everything I read said it was not possible to get a dual boot set up unless you installed Windows XP before installing Vista.
However, I just found this which might help you:http://www.pronetworks.org/forum/about88231.html
The author refers to an app called VistaBootPRO; I know nothing about the app.
If I remember correctly I created my RAID 0+1 array at some point during the Windows XP install.