<SCRIPT>
function greeter(){
if (navigator.appVersion.lastIndexOf('Mac') != -1)
document.write("Write the text for Macintosh users, here ")
if (navigator.appVersion.lastIndexOf('Win16') != -1)
document.write("Write the text for Win16 users, here ")
if (navigator.appVersion.lastIndexOf('Win32') != -1)
document.write("Write the text for Win32 users, here ")
}
</SCRIPT>
Then include this somewhere in the document where you would like the text to appear.
<SCRIPT>
greeter()
</SCRIPT>