Thanks for this advice - I shall dowload it and create a backup of my system (C) drive (all my data is stored on 2 separate mirrored drives) so, as you say, I can restore it if everythig goes wrong!!

I used a bit of software called 'WinToUSB' and it worked fine.

Backup of all data is done. Do you reckon Win 10 will find all my drives when I install on PC drive rather than USB HD which it is on now?

I am brand new to this forum, but impressed with the help available. I have purchased a 64 bit version of Win 10 Pro, and want to replace XP on my PC.

To test out system / program compatibility...