I just copied everything to an external hard drive, then after reinstalling Windows, I installed CoX using my Heroes disc then copied the backed-up files back to their original folders. Worked every time.
If you don't have an external hard drive handy, a DVD-R might still be sufficient.
Sam: "My mind is a swirling miasma of scintillating thoughts and turgid ideas."
Max: "Me too."
Stuff
Worked like a charm. I renamed the directory, installed from the disc and then copied the files over and removed the originals. Thanks for the advice 
Characters:
The Heroic Mary Grace (50)
The Mystical Thunderspark (50)
The Candy-loving Little Jenny (50)
You could just copy the folder over, run the CoH updater, then point to the location your folder is at.
Aka, if you copied the folder to c:\games\city of heroes then point the updated to c:\games\
I have a fully updated copy of City of Heroes / Villains on one of my drives, but due to a system update going horribly wrong, I've had to reinstall my operating system.
Is there a way to get the already updated version of CoX to work without having to reinstall and download everything off the internet?
Characters:
The Heroic Mary Grace (50)
The Mystical Thunderspark (50)
The Candy-loving Little Jenny (50)