Generally I've been hearing good things about Win7 and it doesn't seem to be possible to hold onto XP with new hardware anymore so I'm off to the brave new world soon.
As I recall, CloD wasn't working for you until you did your upgrade from XP, right Dave?
Yes, this was the only reason I upgraded, Clod would not run on XP ; but having done so Im happy
It took me a while but all my old games, hardware and other programs installed fine
remember to save all your savegame or config files from old games, then when you install them into windows 7 you can copy them in and you wont have to start from scratch
you are probably aware of this but you should also save your my documents folder to an external drive and any other valuable folders such as photographs then you can copy them into your new install
windows does a migration tool, see here http://windows.microsoft.com/en-US/windows7/products/features/windows-easy-transfer , I didnt use it as I am dual booting so still have all my old info on an old hard drive on the same computer but it might help you