The only problem with the 2003 version is it can be a pain getting USB external drives (and other modern stuff) to work since it's a dos boot up. That is why some people prefer shadowprotect which uses a pre boot version vista as its boot environment (which supports everything vista does), other programs use Linux which can be a pain as well.
Doing it over a network is generally easier though that too can be very finicky at times. If you have 2 computers its often just easier to hook up the USB drive to the second computer and network it rather then trying to get it to work in dos or Linux.
The easiest of all is of course a second internal hard drive.
Oh and Reece this link should offer some insight
http://nightowl.radified.com/bootcd/bootcdintro.html