Some people use the built in Windows .....
settings and transfer wizard and burn it to a CD/DVD. This is the quickest method I know of, but I have not actually done it yet.
If you don't get another answer here Rob; clicking the "Ask a Queston" may get you faster answers.
The problem in transfering images to another computer is that both computers need to have the exact same hardware. Otherwise the hard drive geometry will be off.
If I had the target computer's hard drive formated properly to the same file system, I wouldn't hesitate to do it using an external drive; but they would have to be identical brand and model computers with exactly the same brand, model number, and size of internal hard drive.
This is assuming all the people who ghost images and backup using external hard drives are telling me correctly that this actually works. I don't see how it could do damage anyway, even if it didn't work. As long as you don't have any data to lose.