Java Applets
If you can't run these applets - you will notice because the one at the bottom of this page will just be a grey rectangle if you cannot - you may need to update your machine to support the latest Java Runtime Environment, which is a free download from Sun Microsystems, from the following URL (Just click on the "free download - Java for the desktop" button in the top right when you get there):
http://www.java.com/en/index.jsp
If you want to check that this is OK beforehand, there is an official explanation and a link to the same site at Microsoft's site at:
http://www.microsoft.com/mscorp/java/