Hi. I lived in Mad Wi for five years. Great city for bicycling, has to be one of the best. Be berry berry careful going eastbound on Univ. Avenue, watch out for the left cross!
I have to agree with others - the Trek 400 is a decent enough frame, but you should look for a good, complete bike. No shortage of them in Madison. Unless you're as- or more-interested in building & servicing, and have the $$$ to buy the minimal toolset you'll need.
If you want folks to ride with, was a good bet back in the day to check out the Hoofers at the UW Union. Fondest Madison memories involve, among other things, the standard Hoofer "Ride to Paoli - Meet at the Park Street Circle at xx o'clock...", and other day trips in the wonderful country to the west. If you're young enough to be one of them.... That's where I learned how to ride, to bring along a flat kit, to equip with rack and panniers, etc.