Everyone has said all you need are rear panniers. I agree, but I also feel having both front and rear panniers is better because it helps balance your load. It also gives you some extra room for groceries. You should be fine with just rear panniers, but if you have the money you might consider a front rack and front panniers as well.

A tune-up tour or two would be a good idea. Ride somewhere for a weekend and see how your load rides, what you need to bring, what you need to leave at home, etc.