Well, hack makers often tell people to be sure to backup the entire database before hacking. Unfortunately this is not so easy for me, because my vBulletin database is like 2.2 GB in size.

...and the server that hosts my forum doesn't have much free space left (prolly less than 2 gigs).
What are the important tables that I definitely should backup when hacking? I know backing up the attachments table is probably unnecessary...