This isn't exactly a Browsers question, but yes, that can be done. When you purchase it, just partition it as you normally would and copy the files to it. Both computers would see both partitions, but that shouldn't matter much as long as you can keep them straight. If you use software to simplify your backup process that would work as well.
I would like to back up 2 different computers using an External USB 2.0 HD with 160GB from SIMPLETECH. I would buy one with more than equal capacity of both computers. (30GB each) Can it be partitioned so each Computer is separated and be treated like 2 External HD's half for each computer? I would connect and back up each one at separate times.
Both are Dell's running XP 2, 30GB HD's, 512 Ram,