PC/Win3.1: Used to be a problematic one, although recently, things are going better for this users group with the release of the 4.xx browsers for Windows 3.1,, the Internet Explorer 4 Java interpreter is slightly faster and more stable than it's Netscape counterpart. 

Mac/os: Still a headache,,,,there are a few flavors of "java capable"  browsers for the Mac,, but after lots of tests, we discovered that only the Internet Explorer 4 does the trick,, the others like the Netscape 3 and 4 or the Explorer 3 has major problems running our Java Chat Applet,,for instance, the Netscape 4 it's able of loading the applet, but it's unable to connect to the Chat server through it.    

AOL: There's a huge bunch of AOL users that are still running the basic America Online internet browser (AOL-IWENG),, which is more obsolete than a 10mb hard drive. We have lots of AOL users knocking on our doors asking "Why isn't my browser neither Java or Frames compatible???",,,,well,  we advice them either to upgrade theirs AOL browsers to the newest AOL-Internet Explorer version,, or to Install any of the commercial browsers (Netscape or Explorer) and use it instead of the AOL one (altough they'll need the AOL software to dial and connect to the net ) 

WebTV's: Altough they are the smallest share of non-standard users,, it's pretty much frustrating to answer them all "Sorry,, but there isn't a way to make a WebTV java-compatible",,,,we will aknowledge them if the WebTV's become Java-compatible (before the end of the millenium).