Mark, I am not an expert but believe the extra parts behind the bulb are both transformer and heat sink as LED's radiate the little heat they produce backwards. I did some Google searching,
here's a site that had a bit of useful information.
Also because of this thread I have started slowly replacing my halogen potlights with LED's. My strategy is mostly to wait for the GU-10 halogen to burn out and replace with an LED. I actually find I prefer the LED light better than the halogen anyway. I have been buying the Philips LED replacement from Home Depot which I believe is just re-badged Cree.
