Two factors influenced the decision to use Linux:

(1) GNU/Linux is just dramatically faster.. and particularly noticeable on the Desktop systems. You don't need benchmarks to see it, even without a pre-emptive kernel compiled or any special optimizations.
(2) Control and the ability to do more and solve problems easier. MacOS X is just far too dumbed down to twist into practical solutions... It is literally not possible to do a lot of things typically necessary in integrating with a larger computing infrustructure... I cannot even limit access to a printer share--all it provides is a checkbox to share or not share.

GNU/Linux with KDE also provides a lot of capabilities unequalled in OS X or Windows GUI systems that make for increased productivity, once you get to know them. For example, network transpearancy in file browsing.... multiple copy/paste... and the Krusader's numerous features such as directory cross-synchronization--very handy for ensuring your notebook files are synchronized with your desktop.

And again.. It's all there... Software you need is usually free..

The only detracting factors are that the Free Software PDF viewers do not always render properly and Adobe Acrobat reader for Linux is only available for x86. And that hardware support for 3D exceleration and sound is lacking on the G5s.

That said, I can plug in any x86 PCI cards and get GNU/Linux support on a Mac where MacOS X often does not. Thus solving the video and sound issues through a little added expense.

Matthew