backup apps

[Robert Holtzman]

I'm looking for backup software that doesn't back up the empty space on 
the drive. Also, I would like it to be able to make incremental backups.
Dump (dd) seems to back up everything, empty or not. Not what I'm looking 
for. I looked at tar but am unsure about the incremental use. I've tried 
Clonezilla but it's giving me problems which the guys on the 
Clonezilla-users list are trying to work out. Can anyone suggest anything
else?

This is for use on a single desktop box with an external HD for backup. 
CLI is preferred but GUI is O.K.

Thanks.

-- 
Bob Holtzman
"If you think you're getting free lunch,
  check the price of the beer"