I don't believe even a standard Java applet (which would run from within the browser) would be allowed to get that info. It plays in a limited sandbox. Almost the same sandbox the browser plays in. Its a security risk to allow a web page access to that info so its been made difficult to get to it.
ActiveX plus IE is one way to go. But its an IE on the PC only solution. You'll need to know how to write ActiveX objects.
You could also build a Java application which gets installed from the web. Then it could share info back to your server. But the user will be presented with a dialog window asking if they really wish to install the software and such.