Yes, I too have had some difficulty with this.
However, I found the answer at http://protolab.pbwiki.com/TutorialProcessingSetup
the whole site is dedicated to this. Good luck
Please let me know if you get the graph program to work.
Whenever I run it, I just get a blank box, where a graph SHOULD be, but no graph or moving lines.
However, in the arduino software, i do see the serial monitor as registering changes in my sensor values.
Very strange why it is no ouputting this smae data to a graph.
If you can help, this would be great!!!