Would I be correct to assume that it's possible to image a SLES, OES, SLED
box in the same way that I can make an image of a Windows box?

Is there anything special to look out for? I'm especially interested in
the possibility of making an Image of a SLED / SLES / OES machine on a
VMWare Workstation box and then restorting the Image to a normal machine
and vice versa.

What can and can't be done. I'm sure someone has tried and succeeded /