Nice post at content consumer entitled The Great Ubuntu-Girlfriend Experiment. Simple premise... using the new Ubuntu, assign a set of tasks to your girlfriend (computer related you perverts!) and see how she does. Click the link for the results.
I tried the same experiment with my 8 year old daughter, but using Kubuntu (the KDE desktop) instead of Ubuntu (the Gnome desktop).
She has been using Windows XP for about 2 years, mostly for games, school projects, looking up stuff on the Internet, graphics and posters (for science fairs and stuff).
I set the menus in Kubuntu to look nearly identical to Windows.
She transitioned without batting an eyelash.
When I had tried the experiment with Ubuntu (Gnome), it was frustrating for both her and for me.
The experiment with the afrorementioned girlfirend was the wrong experiment.