I recommend doing a clean uninstall/install. You can make a copy of the neo-*.xml files found in \ColdFusion10\cfusion\lib somewhere first. These .xml files contain most of the configuration settings you set in CF Administrator. After installing the 64-bit version, make a backup of the clean .xml files somewhere safe, then copy over the ones you grabbed from your 32-bit installation. That way, if ColdFusion restarts without issue, you are good to go. If not, you have backups of clean .xml files to restore from.
-Carl V.
