3D renderring programs, aside from being valuable design tools, can also be a lot of fun. I use a program called Rhinoceros, which I picked up for a reasonable price at a second-hand software store. It doesn't have as many features as 3D Studio Max, but it's incredibly easy to use, and quite powerful.

The official webpage for Rhino is www.rhino3d.com. You can download a time-limmited sample version there if you'd like to try it out.