You can take the train into Munich, either the S1 or the S8, S1 goes to Central Station, and S8 goes to Central Station via Ost Bahnoff. Cost one way 9.60euros or you can buy a day ticket for entire system for 10.40euros, this of course is a better buy. Trip takes approximately 45 minutes one way. You might also be interested in the free tour of the Munich Airport. This is by bus, and takes about 50 minutes, you can inquire at the customer information center in the airport.
Caution....from what I remember, the 10 Euro day pass for public transportation in Munich is NOT valid for transport to the airport...only for the area defined as the "city center"....You should be able to confirm on-line.
Have a great trip...I love Munich, but I would be more apt to visit a beer garden then the museums
