New: Bike-- Looking to Rebuild

I just got a Nakamura Mountain Bike today for free...cost be 11 bucks cdn to get a new tube, but otherwise it works great. The crank, and gear area is a bit dirty and dusty, and there is some rust on the frame. I am a College student, and want to invest a little bit of money on the bike. I actually would like to make it a road bike, if that is at all possible. I want some opinion whether or not the frame is worth investing on, I was thinking about repainting the frame, new handle bars, new rims and tires, new brakes.aerobars. I can get these online for cheap used. But I am unsure if it fits because it is a mountain bike. It doesn't have suspension, and it is called Mt.Everest. Markings I see on the bike are 413_ Triple Butt____??.......something as the sticker is broken. Does anyone have any idea?....I was planning to spend less than 100 dollars on the bike, just me get it to look decent etc. Thanks