ttxuser,
A good idea is to backup the .ptk documents, which are located in:
C:\Documents and Settings\All Users\Application Data\Objectif Lune\PlanetPress Suite 7\PlanetPress Watch\Documents
The .cfg file is good to backup toom, it's your current config, and is located at the root of the Watch directory in:
C:\Documents and Settings\All Users\Application Data\Objectif Lune\PlanetPress Suite 7\PlanetPress Watch
(You could, of course, just do File->Save As to save a .pw7 version of it, it's actually easier to open back up afterwards)
If you've installed any PostScript fonts, the Fonts folder is worth backing up:
C:\Documents and Settings\All Users\Application Data\Objectif Lune\PlanetPress Suite 7\Fonts
If you've downloaded any ppds for your printer, you may want to backup the PPD folder:
C:\Documents and Settings\All Users\Application Data\Objectif Lune\PlanetPress Suite 7\PPD
This is pretty much the most important things to backup, the rest will be reinstalled from the installer if you ever uninstall the suite.
Regards,
Rapha