My advice is along the same lines as everyone else - save up a little more and buy a new bike, preferabley through an LBS. I actually did the opposite and started with a used Raleigh Twenty that I modified. At the time, I had no bicycle experience whatsoever. However, I am a bit nerdy and wanted to learn for myself how to put my bike together. By striking up a friendship with my LBS guy, I was able to modify my bike and ended up with a nice ride in the end. I wouldn't suggest this route for most people, though. Get a new bike and save yourself some headaches.