Thanks for the comprehensive instructions Paul.
I tried that last night and ended up with 2 copies of the SIM720 folder. One in my S drive ( new location) and one on my D drive (original location) with the exception that the original folder had a shortcut symbol with it. I thought that was OK until I realised that all 957MB (459 folders) were still there. (only Oban installed)
I'm sure I deleted the original first, but I could be wrong of course. So I'll try it again over the weekend.
I'd like to know how others (if any) have fared with it.