The last stop of tram 5 takes you to the new center of Amstelveen, to get here with metro 51 you have to take stop "Amstelveen Centrum".
Bus 300 goes from the airport Schiphol via Amstelveen Center to Haarlem. Additionally, many other busses connect Amstelveen with the rest of the world...
More information about the public transport in Holland can be found here (in Dutch but understandable if you are persistent):
http://www.9292ov.nl/ or call 0900-9292 (70 cpm)
or here for Amsterdam and surroundings in general:
http://www.gvb.nl/english/defa









