I try to keep three copies of everything ;) One production, two backups in seperate locations. Currently I have 1 x 80GB in my laptop, 1 x 80GB I carry around when I leave my laptop at home, and 1 x 120GB at work.

I'm looking to upgrade the internal drive in my laptop to 160GB.. the enclosures I have only do <128GB drives.. which means I'll need new enclosures to backup the new drive. I figure why stop at 160GB.. I also want something for, as grahame said, storing videos. And backups of that too.

But yeah, 320 might do.