Well how do you makes these two Operating Systems operate on the same machine, well it is a little tricky and you need at least 2 HDD. This shouldn’t be too difficult.
1. Make sure BIOS can change the boot sequence of drives (if not this trick will not work)
2. Now all you need to do is install Vista on your 1st HDD
3. Reboot and change the BIOS setting to boot to the 2nd HDD
4. Install Linux
Over and done with and now that you have Linux on its separate HDD you can install multiple other Linux distros on that drive since you have Grub or whichever boot loader you have chosen to install. This way Windows has its own HDD it is happy and if you can just change BIOS setting depending on which OS you would like to boot into.
I would like to give a thank you out to John for the inspiration.