It depends. It is doable, but depends on your situation. I spent 4.5 years at college with no car and no bicycle (skateboard and rollerblades FTW!). I lived on campus, ate on campus (for the most part) and either got a ride, walked, or took MARTA to where I needed to go.

As for riding in the winter... the winters here in Georgia are pretty mild. If you have the right gear, then the temperature isn't an issue.
This is what I would consider cold weather gear (45-and-below with no sun, or 40-and below with the sun out)
-Tight fitting helmet with a chin wind-guard
-Balaclava (or bandana tied around your face like bank robbers do) & polar fleece jacket/vest with a high turtleneck collar (to make a good seal so that cold air doesn't sneak down your jacket or up into your helmet
-Cold weather, waterproof textile jacket (waterproof means wind-proof too... you can usually find a deal on a last-year's model for ~$100)
-Cold weather, waterproof -or- heated gloves
-Cold weather, waterproof textile overpants (layers will keep you warm)
-Riding boots (something that covers most of your shin)

Most of your late fall and winter weather riding will be done in the mid-to-high 40's, so leather will keep you warm enough most of time (especially if the sun is out).

You will need a good backpack and cargo net/bike luggage to haul the occasional item (food, etc).

You will also need basic tools (or a friend with tools) for periodic bike maintenance (like getting new tires mounted).

Last, you will need a safe place to keep your bike because they do get stolen. I would not bother owning a motorcycle if you live in an apt or have to park it in any kind of mass parking lot/deck