I know, I know, long overdue, but here it is anyway: a little tool to assist you in building and running a "freeform" project (existing Ant script) using a different JDK from what NetBeans is running on. Ant tasks like javac and the like have long supported selecting a particular JDK executable to use (means they must fork to run the tools), but few people would want to remember to set these attributes consistently. Instead, this tool uses the magic of presetdef to do it for you. The upshot is that freeform projects behave a little more like other projects.
Freeform Project Extras 1.5 NBM
(NetBeans 5.0+ compatible)
If you were really paranoid you could make your test target run all your unit tests in turn on each supported JDK...without leaving the IDE. But that's for you to write.