The hard disc is just a regular laptop (2.5") hard disc. If you were feeling brave, you could open up your jb3 (I think in the FAQ there is a link to how to upgrade the HDD, follow those instructions... CAREFULLY). With a 2.5" -> 3.5" adaptor you'd just plug that into your PC as a 2nd hard drive (obviously choose an unused IDE channel or set the drive to slave mode). That should appear as a new drive to your PC, and unless is it totally fucked you may be able to pull some info off it.
At a pinch you could pass the drive onto a company who specialise in data recovery. Those guys can sometimes work miracles (for a fee, of course).
Pop a new HDD in your JB3 and you should be set... good luck!
best regards,
stephen