Okay, so I just brought an external hard drive and am currently formatting two partitions, a 20GB one (for XP) and a 50GB one (for Vista). I'm planning to backup files and then reinstall Vista on my desktop along with all the usual programs and music I have and then do it again for with XP for my laptop. What I wish to do is create a bootable ghost image of both hard disks and save them to the external one. The only problem is, I do not know how to create a bootable ghost image. I'm also wondering if it is even possible to create a bootable ghost image especially when the it is a USB hard drive.

If the purpose for making a bootable ghost image is to save the partition for later restoration, then this is easy to do with several 3rd party apps. If it's for the purpose of booting the image off of the USB drive, then it's not so easy to do.

Acronis True Image (approx $50 US) will allow you to make an image of your hard drive, and will also have you make bootable media (a CD/DVD) so that you can boot from it and restore the image off of the USB drive. I haven't tried any of the freeware applications that do this, so I'm afraid I can't recommend any (check this topic for some suggestions: http://www.bleepingcomputer.com/forums/topic3616.html

If you want to boot off the USB drive to reinstall the image, then that'll be more difficult. You'll have to make the USB drive bootable with an OS that will recognize USB devices and will match with the image software restore program.

If you're just trying to boot to the OS on the USB drive, then that'll be even more difficult (and I don't know about doing it with Vista). I considered trying this with XP at one point (and found this article: http://www.ngine.de/article/id/8 ) but found it to be too much trouble for me.