Distribution Upgrade Help Needed

[Rich Shepard]

   My wife's laptop is currently running xubuntu-8.04. I just finished
upgrading all installed packages using Synaptic. However, it did not offer
me the option of upgrading the entire distribution to 9.04 and I don't see a
menu option to do so. I run Slackware on our other hosts so I have no idea
how to upgrade the distribution from within the GUI.

   Should I su to root in a vitural console and run 'apt-get distribution
upgrade' or take a different approach?

Thanks,

Rich