When enabling the Java applet from IE, just IE requires a restart -not Windows itself. Once you have restarted IE the Java applet is enabled. However, it should not be necessary to enable this from IE. If you install the J2RE the plugin should automatically be enabled . You can test this by going here:
http://www.java.com/en/download/help/testvm.xml
The J2RE is now at 6 (
here). See what happens by just installing the latest version and going to that link above.