The default tep.jnlp file works great in certain environments, and not at all in others. Basically, it works if you only have Java 1.4.2 installed, or if you have Java 1.4.2 and Java 1.5 installed. But things don't work so well if you have Java 1.6 installed. This change fixes that problem.
What I did was change the line that reads:
j2se version="1.4+" size="64m" args="-showversion -noverify"
to the following:
j2se version="1.5*" size="64m" args="-showversion -noverify"
If you save this file with a new name, you must also update the line in the file that references itself (i.e. change 'href="tep.jnlp"' to 'href="newfilename.jnlp"').
And I found that ONE of these two files (the original or the changed) will work for almost all users. They just need to try one, and if that doesn't work, try the other. The problem is that the Java 1.4.2 browser plugin doesn't support the changed syntax. So you can just tell your users to try the first, then the second.
Edit: If a user only has Java 1.6 installed, the changed file will work and will automatically download and install Java 1.5.