You've got a good bike there, enjoy it. I have the similar Gary Fisher model, the Utopia, and the thing is pretty much bomb proof. I find that I give up 2-4 mph between the Utopia and my road bike. Halfspeed's comment on flat bars vs. drop bars are right on the money. My hands are definitely more comfortable on longer rides using the drops rather than the straight bar. If you find that you have some trouble with numbness, be sure that your wrists are straight - if you tend to bend them downwards, numbness will result. Also, try moving your hands near the stem from time to time - that at least gives you another hand position to use.
Enjoy your riding and don't worry about weight, worry about the engine!