Suddenly I realize after actually looking a little closer that Mozilla 1.7 isn't listed as supported... Should that make a difference?
Edit: I used the ns610-gcc32 version of the plugin rather than the regular ns610 one and the java applet will load and run but it's extremely choppy...
The applet I tested it with was a Slime Volleyball game that is really well made and quite fun. This is the link to it:
http://www.student.uwa.edu.au/~wedgey/slime1/ . Is it just me that gets poor performance on this? Or is there some sort of known fix that will make it lay normal?