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>=8)
  document.write("<link href='/style_ie7.css' rel='stylesheet' type='text/css'>")
 else if (ieversion>=7)
  document.write("<link href='/style_ie7.css' rel='stylesheet' type='text/css'>")
 else if (ieversion>=6)
  document.write("<link href='/style_ie6.css' rel='stylesheet' type='text/css'>")
}
else
 document.write("<link href='/style.css' rel='stylesheet' type='text/css'>")