I recently bought a (pretty old I think) used Norco brand mountain bike. It seems sturdy, isn't rusted or anything, and rides pretty well, but the more I use it the more I want to invest time and money into fixing it up--it could use some new chainrings, etc.
My question is whether the frame is decent enough to warrant the effort, or if I am better off finding a newer/different frame and/or bike to invest in.
A picture of the bike can be found at http://yfrog.com/16b46rj. I can't read the original bike model. The most individual characteristic seems to be the placement of the rear break (it is down near the chains rather than near the seat post where breaks most often are). I don't know if anyone will recognize it.
I wouldn't upgrade parts, but some parts may need to be replaced because they are simply worn. Not knowing how much you ride or if you are new to cycling may make a difference on some advice. Assuming you are new to cycling ride the bike and get in shape. You will figure out what type of riding you want to do. There are certain "upgrades" you can make to the bike like a saddle bag, tire pump, fenders, and/or rack. These items you can buy now if you have need for them, then later if you buy another mtb you can transfer the items to the new bike if you need to.