I was unable to back up my 770 through Nero BackItUp 1.2.0.23. Just like Windows Explorer in XP, it recognized the FAT partition on the MMC, but not the other partition that has the boot/OS stuff on it.

However, I was successful backing up using Norton Ghost 10. Connecting my 770 with a USB cable, Norton recognized the partition and allowed me to back it up.

Note that this only worked using the USB cable. Removing the MMC and putting it into a card reader did not work.