I have acquired an used external HD (a WD Passport) that I'm planning to use for the backup of important files - I was thinking of using it with Déjà Dup.

Should I format it beforehand? Which partition type would make sense? Should I go for the "Don't Partition" option? All of this is supposed to be done trough the disk utility, right?

Sorry if the questions seems somewhat silly - I'm definitely not very savvy regarding these matters.

Thank you very much. Done as suggested, formatting the whole thing as ext4. A separate 700 Mb partition with stuff from the HD producer (instructions, an automated backup program for windows etc...) seems to have survived. Should I go after it or leave it be?
The disk is pretty big and I backup mostly texts, so I'm not really craving for more space.

Another question: would the ext4 interfere with the recovering of the data in the HD by using a non-unix system? How much of a hassle would that be?

Thanks again!