Jmol is a new system for viewing protein structures from within a WEB browser (though it also runs stand-alone). Jmol requires a newer generation browser, with JAVA and JavaScript enabled. On Macintosh computers, this requires Safari (at the moment, ONLY Safari will work - not Netscape or Internet Explorer). In Windows computers, a variety of browsers are supported, mostly (FireFox works best). On Windows, if you haven't already, you'll need to install Sun's JAVA run-time environment.