so this past month or so, i have begun a bit of mountain/trail riding. LOVING IT. im on a gary fisher zebrano hybrid and i love my little guy. its obvious to me, however, that having nubby tires is going to help me on the trails. everyone in the group ive been riding with claims to be very impressed with how im doing thus far, but .... i think i can do better and enjoy it more with the 'right' tires.

that said... i keep getting yeses and nos on whether or not i can put nubbies on a hybrid bike (and if thats the case, can i put road tires on it too?). im preferable to not changing wheels, as i am pretty damn broke; just the tires.

also, im looking at graduating to clipless. since i am a big fan of ANYTHING hybrid (car, bike, job. gotta love the "best of both worlds" kind of thing), the local shop recommended a pair of shimano cliplesses (h didnt have the model number on him, and since i was already there five minutes past closing, i didnt want to push it) that has the clipless on one side and regular pedal on the other. any thoughts on those?? is it a waste of my money? id like to have something to actually ride with, and something to "kick it" with when i am just tooling around. are pedals so easy to change out that i shouldnt bother with those -- and just keep the OEMs and change from clipless to OEMs as needed?

thanks!