Backup the 8390's Firmware
(I think that this can work with ANY Windows Mobile powered device, even Pocket PCs)
Follow this simple steps for backuping your firmware!
Download the rom tools
Unzip it in a folder
Turn on your device and connect it in the cradle
Make sure that activesync is running (wcescomm.exe in the task manager)
Run sign.bat for sync deivce certificates with pc. (This operation can be done one time in the os life)
Run backup.bat. (maybe edit it for setting a different name)
Operation is done! For flashing it again use farur02.exe
If you want to extract the ROM contents, use dump.bat (edit it depending on your necessities)