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)
	document.body.style.backgroundColor = "black"
else
	document.write('<img src="images/background.jpg" class="bg" />')
}
else
	document.write('<img src="images/background.jpg" class="bg" />')