The parts that may or may not swap over are as follows and why:
The forks: Different frames and different size frames have different head tube lengths. If the steerer tube on the fork is too short it will not be able to be mounted on the Jamis.
The seatpost: The Denali is Alum (I believe) and the Dragon is steel (Steel is real baby) The seat tube may be of a different diameter. 27.2 is pretty standard for alum. frames, but steel us usually smaller like a 26.8.
The front derailleur: For the same reason as the seatpost. The seat tube may be a different diameter. Some of the newer front derailleur clamps have an adjustable, so you might b o.k. However,due to cable routing of the two frames the swing of the derailleur might be different. The good thing is front derailleurs aren't all that expensive. I've seen XT's on line for $15. As a matter of fact I have a brand new XT front for a steel frame N.I.B. if you need it, let me know!
Chain. If the chainstays on your Dragon are longer, you may have to add a link or two to your chain.
The bottom bracket shell width varies as well. Some are 68 mm and some are 72. Again some of the newer bb's have spacers to accomodate both.
Everything else is compatible.
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