if (/MSIE (\d+\.\d+);/.test(navigator.userAgent)){ //test for MSIE x.x;
 var ieversion=new Number(RegExp.$1) // capture x.x portion and store as a number
if (ieversion<=6)
alert ("You're using a very old version of Internet Explorer which will not allow some of BLACK KNAVE'S features to work properly. Please upgrade to Mozilla Firefox, Apple Safari or Internet Explorer 8")
 
}