Kevin,
The information provided by Tim is about the same that I was going to recommend. The beaches and battle sites are spread out over a large area, so walking is not really the most practical way to see them.
I would also highly recommend a BattleBus Tour. I've taken both the Canadian and U.S. highlights tour, and they were both outstanding! As previously mentioned, if you're planning to tour with BattleBus, you WILL have to stay in Bayeux on the nights prior to the tours. Bayeux is a great "home base" location for touring the important sites. One point to note is that BattleBus is very popular, so pre-booking would be a really good idea!
Some other locations that you might consider are the Gun Batteries at Longues sur Mer, which is only about 15-20 minutes from Bayeux, which were used in the filming of The Longest Day. I used a car rented in Bayeux to visit, but you might be able to arrange a Taxi or something as an alternative?
There's also the Pegasus Bridge sites which are closer to Caen, but unfortunately those aren't covered on the two BattleBus tours mentioned above. You could arrange another tour if you'd like to visit there, as I believe BattleBus does stop there on some of their tours.
As you're a "WWII buff", my suggestion would be to forget the idea of walking, and try to maximize the number of places that you see in the two days you have. You'll learn far more than just having a look on your own.
Of course, if you're staying in Bayeux, be sure to stop and see the famous Tapestry which depicts a much earlier battle.
Happy travels!