Well I had a challenge recently setting up Vista on a new box.   I used an older hard drive (40GB) in it for the boot drive.   The BIOS clearly showed it just fine as first boot device, and the Vista installer showed it in the list of hard drives, but there was a warning stating that Vista couldn't find a suitable drive and to check the BIOS.   This was quite perplexing.   I could format it and set it up, but it wouldn't proceed to installation since it said it wasn't bootable.

The drive was an old Samsung one and on every boot it would display a message about Ontrack Overlay Manager.   I read somewhere that Vista doesn't like this overlay.   I found a bootable ISO image to enter Ontrack tools on the computer (the smallest ISO image I've ever downloaded at 1.5MB!).   From there I had to first wipe the drive, then I got an option to Remove Drive Overlay.   The point of the overlay is to allow older computers to recognize drives greater than 32GB.   Yeah, that's how old it is!   Once I removed the overlay, everything proceeded just fine.   It was lower-level than formatting so I guess that's why I needed the special tools.   Unfortunately I wasted a few hours trying to figure this out!