now Ejs has a couple of applet that has Maxwell Speed Distribution Law too.

Ejs Open Source Ideal Gas Model with Maxwell Distribution of Speed Java Applet by Wolfgang Christian
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1482.msg5554#msg5554

Ejs Open Source Ideal Gas Model based on Kinetic Theory of Gas by Fu-Kwun Hwang from Francisco remixed by lookang
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1455.0

check out out 2 man :)