Undo dual-boot between Vista32 & Vist64

I've read several threads with people dual-booting between 32bit & 64bit
VISTA so I know its possible. I would like to try that as well with VMWare
Workstation under Vista64 (mostly for the greater memory space) . I have
another drive I can use for the Vista64 install and (hopefully) not disturb
Vista32 in case I want to go back. Suppose I do want to go back. Can I just
take out that new drive and reboot or must I do something to make it boot to
Vista32 as before? I don't want to have a "dead" entry in the boot menu.

Also, I have a RAID card in my machine with a RAID 5 setup as a D & I
drives. They show 32bit & 64bit drivers for VISTA. Will I be able access the
same "data" drives from both operating systems?


Thanks
Steve