A hybrid would be a good choice, but if you're set on a road bike then maybe a cyclocross would do you better, though I imagine finding an older cyclocross would be harder than finding an old roadie. If you could give us your budget, that would go a long way in deciding whether or not you're in the new bike range. A late 70's to 80s bike would probably be perfect for you, they're plentiful and often a good deal if you know what you're looking at.

But if you're going to use it mainly for that 3 mile commute, then a road bike would not be necessary, a non-suspension mtb would suit you just fine. Or you could get a singlespeed/fixed gear bike, being around a college, I'm sure there's a bunch of them for sale in craigslist.

Being a college town, you need to get yourself a cable and a good quality U-lock. put the u lock between the front wheel, fork, and the item you're going to lock it to. And run the cable through the U-lock and through the rear wheel.