The Count To 1 Million program will function on any computer running Java 6 (version 1.6) or later.
Most Linux and Windows users will probably already have Java. You can download the latest Java from Sun free of charge at http://www.sun.com.
Mac users can get Java 6 for OS X 10.5 and above with 64-bit Intel processor from Apple at http://www.apple.com/downloads/macosx/apple/application_updates/. The Count To 1 Million program has not been tested on Macintosh computers yet.