Glyn, sort of related to what you are saying; I have the Win 8 upgrade purchased but I am holding off for a while to install. I thought I would wait for all of the drivers and bugs to be worked out before I attempt the change over. The PC that I bought from Best Buy a few years back came with Vista 64, but I don't believe that I have the serial numbers anywhere. At least, I have not located them. I believe that means I am going to have to install over Vista and reinstall all of my programs. I am also in the process of getting all of those serial numers organized so that I don't lose anything.
There may be easy ways to do all of this, but I am not very techy with computers. This is still a very usable machine though, Phenom X4, 8 gig ram, 500 HD.