Sorry for the late reply, but I second Google Sketchup. It's the easiest to learn and they have around 30 tutorial videos about 20 minutes each. I only watched the first 2 and I was up and running.
You know, open source 3D Printer designs are pretty good these days. I'm surprised not everyone in the group has their own with all the DIY prototyping going on. Seems like a natural extension for this group. I just finished building one with a 1 cubic foot print volume for
about $800 that has about the same print quality as the expensive ones at Tech Shop.
If anyone wants to check several of them out, there is a weekly South Bay RepRap 3D Printing group that meets at San Jose Tech Shop on Wednesdays at 7pm. You can find them on Google Groups. You don't need to be a Tech Shop member to attend the meeting.
Ken