Microsoft Windows 98 or better, or Macintosh OS X or better, or Linux; Internet access, e-mail, the Microsoft Internet Explorer or Mozilla Firefox Web browser, and the Adobe Flash and PDF plug-ins (two free and simple downloads you obtain at http://www.adobe.com/downloads by clicking Get Adobe Flash Player and Get Adobe Reader). You will also need a working copy of the most recent versions of the Java Development Kit (JDK) and BlueJ (free downloads). Download and installation instructions are available in Lesson 4.