How to backup your Data and restore...
Download this...(again, read directions)
[TOOL] WP7 Easy Backup Tool (BETA) - xda-developers
You'll need the Windows Phone 7 support tools (link on the thread above) and the newest version of Zune.
This tricks Zune to think there is an upgrade, to take a backup of your device (backs up everything but, media, music and videos do not get backed up).
once backed up the file is stored in(win7)
%LOCALAPPDATA%\Microsoft\Windows Phone Update
To restore, just open up the program and and click restore (it will restore the image at the location above).
Something to note and READ !!!
If you use the factory rom from above, it will restore you back to 7392 (NoDo), if you attempt to restore, IT WILL FAIL. You need to be at almost the same level. If you were restoring a 8107 backup, you need to be on Mango at least or it will fail. This could result in installing the factory rom, and upgrading to 7740 (mango) then restoring. Just a heads up....