Want to back up both internal hard drives on mac?

My Book Essential 750gb connected to G5 Mac (powerpc) running tiger

I have 2 internal hard drives 1 x 160gb has all programs on it  and 1 x 250gb has all my documents, photos etc. on it.

I installed the My Book (had to reformat for mac) yesterday and it is working fine but it ONLY BACKS UP MY 160gb hdd how do I get it to back up both hard drives or at the very least change it to backup my 250gb hdd with all my docs. and stuff on it??

any help would be greatly appreciated thankyou:smiley:

Which backup software are you using?