GEDCOM Viewer will run on any system that supports Java(TM). This includes systems using Microsoft Windows(TM), MacOS X(TM), Linux(TM), and Unix(TM) systems. To run GEDCOM Viewer requires that you have Java Runtime Environment 1.5.0 or better installed on your computer.
If the Java installation on your computer is not up-to-date, then use this link to get a free download of the latest version of the JRE, Standard Edition from Sun Microsystems.