Thanks for the help all- I will check out that book at the library as well.
I found a mountain bike with a front disc, full-suspension etc for $20 at an estate sale; I have no idea what it is but I will put a light and tool kit on it, give it a tune-up and have at some trails. If it breaks, so what it was a $20 investment and I can salvage the parts i put on it and some of the parts on the bike originally.
Nothing will turn me away from mountain-biking however, I used to ride terrible (rocky and mountainous) terrain on a BMX bike so whatever happens, it won't turn me away from the sport.
What about securing things like lights and tool bags for the stresses of off-roading? I have a light set with plastic clamps and rubber inserts that does fine on the road but seems like it wouldn't hold up to the stresses of bumpy, hilly terrain. Same with the underseat tool bag.