Advice Please - Partition Setup for Dual Boot

I have 3 harddisks in my desktop PC configured as individual disks (ie
non-Raided) attached to a SATA raid controller. WinXP is currently installed
on Drive 0. Drive 1 is configured for all user data (My Documents etc); and
Drive 2 is for backups.

What do the panel recommend for re-configuration to create a Vista Dual Boot
system?

I already tried once, by creating a new second empty partition on Drive 0;
booting the Vista DVD and configuring onto this partition. This worked quite
well EXCEPT that the Vista Boot Manager stuck itself on the WinXP partition.
I would like to AVOID this if possible since at some stage in the future, I
want to delete the WinXP partition and extend the Vista partition to use the
whole of Drive 0.

So, how to do this install?

Thanks
Nigel