Thought I would post back with my experiences.
I bought the ShadowProtect software for $99 and it is diabolical AVOID!!!!
After fighting my way through a dazzling array of products on a website that was obviously designed by the same guy who did the Siemens site, I parted with my hard-earned. Got the software and then was told that it doesn't do what I wanted. Which was to back up a PC without installing the software on the actual computer.
I decided to just install it on a test machine to see if it would work but then found out that you can't do that either as the machine needs access to the net (which in the factory the PC doesn't have). Also, to activate a PC 'offline' you need to contact them and they basically send you a patch to install.
After spending a good half hour talking to various help desk people who didn't even know their own product range I decided not to trust the fate of our factory to these people.
I returned to this thread and found a recommendation for Paragon
http://www.paragon-software.com/home/br-free/
It's free and it does everything I wanted very easily and quickly with a great 'wizard' to help things along.
Just in case anyone is in a similar situation as me and is curious, it took about 15 minutes to backup a PC with around 8Gb of data on it (but the SCADA still ran fine in the background whilst the backup took place).
Well done Paragon.
Shame on you ShadowProtect.