Upgrade Mac OS for 129$ to run jEdit???

> MacOS X
>
> jEdit versions earlier than 4.2pre9 have problems
running under
> JDK 1.4.2 on MacOS X. Use jEdit 4.2pre9. Also make
sure you are
>running the latest OS patch level and MRJ update.

This can't be true! I have to upgrade my OS just to be
able to get JDK 1.4.2 which seems to be required by
jEdit?? How can I get 4.2pre8? Will 4.2 run unde JDK
1.4.1 too?