I've just been round a similar loop and it transpires that Netscape (up to 4.96) runs Java 1.0, Java 1.1 for Ver 5 and above.
IE 5.5 runs Java 1.1 (I suspect IE 4.0 up, too)
Versions of Opera I am not sure.

MTMLkit reports that my HTML appears to be compatible with HTML 3.0 which is fine by me as the whole excercise was to ensure as much backward compatability.
Even Casio UK forced me to load Flash just to find after 5mins they weren't even upto date on their products. It is a real turn-off if the clever stuff looks stupid.