Hi Steeple,
I loaded up a VM instance of this for you on Win2K8 SP2, and was able to load and utilize JDM 6.2.x on an ERS4500 with no issues whatsoever.
My instance has a dual xeon 2.2ghz, and 2Gig RAM and runs great.
Not sure what trouble you had or whether you were just being conservative prior to a rollout, but it appears safe to roll forward.
I hope this is helpful.
-HH