File-system for backups? I've got a fresh 2TB external hdd (pre-formatted with vfat) which I'd like to use for backups.

What file-system should I use for that purpose? Since it's meant to be a backup drive the fs should be rock solid.

The system drive is ext4 formatted. However, I heard it has some risky features that can screw the file system in case of power loss. How about ext3, or Is there something better?

I've still got Windows XP installed, but it hasn't been booted for about half a year and there's no valuable data on the windows partition. (Only a few games.) How good/bad is ntfs for backups? 

I plan on using `rdiff-backup` which stores meta-data separately. Therefore, permissions and such shouldn't cause any trouble.