1. Do a synchronization to backup the Palm spreadsheets to the PC so that you can restore them later.
2. Run the Uninstall program of the Addition4Palm menu group (path for Windows in english: Start_Menu>Programs>Addition4palm>Uninstall) and delete the Addition program from your handheld device. (make sure you're not running excel on installing and uninstalling)
3. Run the setup program you have downloaded and follow the steps of installation.
If you run into any problems, ask for help.