ONE OF THE BEST WAY TO BACKUP YOUR PIM FOR FREE IS TO SYNC IT TO A SERVER (NO DEVICE/S LIMT)
YOU CAN USE ONE LIKE THIS
mail2web Live
AND ONE MORE OPTION YOU CAN FIND ON THE "OUTLOOK" THREAD
USING THIS FREEWARE
emoze Free Push email, mobile email software for mobile devices.
YOU CAN USE EMOZE TO SYNC YOUR HOME OUTLOOK OVER WIFI (ANY INTERNET CONNECTION)
HOPE IT HELPS