There is a known issue where the web site will not launch a tour or search if you are using FireFox or Safari.
Solution:To See a Tour, open WorldWideTelescope and go to Guided Tours tab and you will see a list of tours that you can run in the application.
This solution is unacceptable. There is no good reason why this should not work in *any* browser, not just in Microsucks IE. It does not work in Opera either. Way to go.