Your support person you spoke with wasn't thinking multi drive, only the single internal hard drive configuration.
Boot Camp Assistant will actually ONLY use the entire drive. So some people put a small OS X partition on it to force it in two.
I would play around, practice. But if you get familiar - can't hurt and always only helps - Disk Utility => Partition tab => Options.... (bottom of screen) and change it from default "GUID" to Windows Boot Record. Create MSDOS (FAT32).
Vista will install just fine, and gives you the option to format / delete and create - but if it is on its own drive it usually complains about "GPT" due to the presence of OS X drive. That is easier to do than describe / explain. There is an Apple and MS tech note though.
I like the OS to be on the outer tracks, higher performance. The idea of putting an OS on the 'backend' where I/O is the slowest is just.... sluggishly slow and I'd never want or put OS X there for regular use.
Also, once you have Vista, it is a lot easier to install a 2nd system, like "7" on another drive or partition; rather than boot and run from DVD, copy DVD easily to disk and it is lightning fast. Down the road.
You should be able to just boot from Vista even without doing anything, just remove OS X, treat it like a PC, and install. Works best if the drive is raw and was never formatted in OS X even.