I'm using Kubuntu as well.
I use LuckyBackup which I was able to install using the repository, it's pretty
intuitive and there's a great tutorial on UbuntuDocumentation for it. Right now
all I'm doing is a manual backup once a month, first to another place on the
local hard drive and then from that backup to a USB drive.
I'd really like, however, to get a more automagic Rsync solution that I haven't
been able to find yet.