I backup my xbmc config on my raspberry pi with Linux and rsync.
On windows it's unfortunately not that easy. That's why I describe in the following paragraph how to create a backup on windows and how to restore a previous backup. In addition I provide two windows cmd files which execute the commands in sequence and make the backup and restore much easier. Three tools are requiered on windows: putty, pscp und plink which can be downloaded from the putty page. If you kick off the backup command with the at command on windows you will have an actual backup all the time.
tar -czf backup.tar.gz .xbmc/
pscp pi@pi:/home/pi/backup.tar.gz .
pscp backup.tar.gz pi@pi2:/home/pi/backup.tar.gz
mv /home/pi/.xbmc /home/pi/.xbmc_org
tar -xzf backup.tar.gz
sudo initctl start xbmc
rm -rf .xbmc_org