An external hard drive needs to connect to the PCI bus, not the USB bus, in
order to boot a Windows OS. I use external SATA drives connected to SATA
ports on the back of my test computer. I booted Vista all through the beta
this way because the arrangement is equivalent to having additional SATA
connectors on the mobo. I beleive that the same arrangement works with scsi
drives as well. USB drive enclosures cannot be used in the same way.

"Iplant" <Iplant@discussions.microsoft.com> wrote in message
news:244A395C-64DC-41CB-8B5F-7B53671504A9@microsoft.com...
> sorry...I recently purchased a W/D Book (250) external hard drive...seems
> to
> work great on XP but Vista is now very slow to boot up. The screen is
> black
> for a good 20 seconds before loading. Does anyone know why? Anything I
> could adjust?
>
> Also; I am curious, could I install Vista to this external hard drive
> using
> the full version and leave XP installed?
> --
> always learning