I'm trying to have an additional drive with vista installed for back-up, recovery, problem solving etc... for my laptop. So I tried to be smart, and installed Vista on a SATA hard drive that was connected to the SATA cable of a PC. The HD was then put in an enclosure connected via USB to the laptop. However, when trying a reboot on the USB drive, it got started (which means it recognized the System on the external HD), then the loading stops with a blue screen and the machine get restarted. I believe there should be an incompatibility in the way vista was installed (as a main HD "C:") and the way it tries to load (as an external HD "F:"). I have no clue how to repair the installation on the external HD, I tried the "Repair" function from the vista DVD but it didn't help, same problem after repair. May be things have to be repaired manually?

any help will be appreciated.

I don't believe you can boot Windows o/s via usb.

You would need to attach the drive to the laptop via sata cable, install it from the laptop itself - then to boot it , it would also need to be sata connected.

If you want to use an external usb HD for recovery purposes - the best way is to store disk image backups on it.

The free version of this is excellent:

http://www.macrium.com/reflectfree.asp

Hope it helps