I use Linux and OS X as my primary operating systems. Lately I have been using the Powerbook exclusively with ssh or FreeNx to work on the Linux machines on the network.
I started off to simply repartition my Powerbook and then reinstall OS X and put Ubuntu on the new partition. That was two days ago. Things are pretty much back to normal now. I have a dual boot system that I can take with me and run my favorite GIS software on both platforms as needed.
The Ubuntu install was easy, although a bit different than on Linux. Overall it was pretty smooth, including the installation of the boot manager. Of course the downside is you can't use the AirPort wireless in Ubuntu (or any other Linux variant) due to the proprietary nature of the Broadcom driver.
So why did it take so long? First off I copied everything off the Powerbook to an external USB drive for safe keeping. This was a slow process. Restoring things and reinstalling all the OS X applications took a while as well.
The biggest problem was getting printing to work. This may or may not have been associated with the dual boot hack, but it popped up about the same time. The printer is attached to a Linux box and in the past used Samba to provide print services to the other machines on the network. This didn't seem to work anymore. Every print attempt from OS X resulted in "the smb process terminated unexpectedly". Several hours later had printing reconfigured to use IPP. The only remaining problem was that jobs were not removed from the queue on the Linux box after printing completed. Right or wrong I finally changed the permissions on the /var/spool/cups directory to give group lpadmin write privileges. The cupsys daemon in turn changed the permissions and removed write from lpadmin on everything except the tmp subdirectory. This solved the problem.
Now maybe I can get back to doing something more productive...