If I were you I'd download and install the latest NMSDK. All of the releases that I've tried have remained quite backward compatible with older tools like DFM/OM, so I think you'll be OK. We just got rid of OM a little over a year ago, so I know of what I speak. The newer releases also have the advantage of being more secure due to upgrades in the underlying bits-n-bobs.
I will note that I've never used the "Java Version", but I would hope/expect that it was equally compatible.
Good luck!
