So, you've gone through the boot camp wizard and have prepped your hard drive for boot camp. When you run the Vista installer, you get an error indicating that your drive either can not be found or is not suitable for use.
How to fix it? Well, it's really easy. Vista supports EFI so crack open the case on your mac pro and pull out the startup disk so that the only drive "hooked up" in the system is your Vista Hard Drive.
Boot up, install windows, and then put your Mac Drive back – easy as that.
Hope this helps 😉 I've seen many more convoluted solutions and this one appears to be the easiest.