Ok, so background is that I have one desktop machine that is running Win7, that I would like to take advantage of the Win10 offer with before the 'free' period expires.

The machine was built 3Y ago but is well spec'ed, except that it has a mechanical hard disk.

I'd like to get an SSD, and install win10 onto that, in a sort of dual-boot environ. I don't want to lose the Win7 setup yet... because I'm not the only user, and I need to be considerate of my wife and her needs for using the computer too (she does not like change like this). 

I'm fine with Win10 and have used it for a while...  while I'm confident the above can be achieved, searching google for articles brings the heavy indexing of people that did this when Win10 was at preview stage, and not reflecting state of play in 2016.

So some thoughts from the community here would be nice...