...then set the bios to boot from the vista partition...
You've got a BIOS that can read into different partitions? I didn't know they could, or maybe that's just me.
My advice would be the same advice as to someone wanting to try linux:
Get A Separate Disk. (try your local Console-Modding shop, they practically give away 10gb HDDs from old xboxes)
Disconnect all drives with any other OSs and boot partitions on when installing vista. I'll never trust anything windows can do to your boot partitions, especially on pre-release software. Maybe keep your 'data' disk connected while installing, as long as you don't accidentally format it (it's happened before). If vista destroys your boot partition, then you haven't lost much (even if it is only time figuring out how to fix it).
IF everything installs properly, and works fine, THEN you can think about reconnecting your old win drive, and choose which drive to boot from in the bios.