Or you can try
http://www.gentrycitylimits.com/DemoSoftwareA.htm for a demo of Bryce 4. The setup the guy's got for downloading/installing it is a bit annoying, but I'd personally recommend it for beginners. It's only real drawback is a lack of export capability, so there's really no way of getting Bryce models into .X format. I've just posted a question on the Bryce forum to see if the upcoming Version will address this or not.