I just bought a mountain bike about 3 weeks ago. Ive have some bike paths through the subdivisions where I live that I have been riding. I have also ridden Alum Creek P1 twice now and plan on going tomorrow morning. I will say I enjoy the challenge of riding the trails much more than riding on the street. Luckily I live less than 10 minutes from two trails so the convenience factor isnt a big deal. I will be looking into a road bike in the future as I could see that being very enjoyable as well. Hidden costs...I bought bike shorts with gel and they help alot. I just upgraded my pedals today as well. You can always ride your mtn bike on the road but not a road bike on the trails. I will say definitely buy a good lower end bike from a good manufacturer...trek, specialized, fuji, giant, etc. I found a 3 month old Specialized Hardrock with disc brakes for $300. The bikes take some abuse on the trails so definitely need/want a better bike. I would also look for something with disc brakes. You could upgrade one with rim brakes but the disc ones are more expensive and you'll want good brakes. Thats my limited knowledge from someone just starting out so....