There is a small 'backup' battery inside the M2000 (M1000 is the same) the retains your data for about 30 mins for when you replace the battery or run out of juice. Just makes sure you have your other battery handy!
There is a program on the M2000 called xbackup. If you use this you can back up the entire handset to the 'Storage' memory. The storage folder is part of the ROM and is non-volatile. If you do run out of power away from your PC you can restore from the storage folder with xbackup. I backup to my SD card too!