openjdk-7-jre and Iceweasel

[Lisi <lisi.reisz@gmail.com>]

I am trying, without success, to run:

http://media.pearsoncmg.com/aw/aw_kurose_network_2/applets/dns/dns.html 

The problem is the applet.  The Java I have on  my Lenny system is too old.  
Hardly surprising.  So I switched to Wheezy.  Still not OK.  I checked: I 
only had openjdk-6-jre.  So I installed openjdk-7-jre and its dependencies.  
Still no joy.  I imagine that iceweasel is not using it at all, or not in the 
way that jre 7 needs.  What can I do to run this applet?  This is a course in 
OSS, so it shouldn't require anything proprietary.

Thanks
Lisi