var IE5 = (DOM && (navigator.userAgent.toLowerCase().indexOf('msie')!=-1) && !(window.opera));
function Inicio () {
if (IE5) {
   Dimensionar();
}
}

function Dimensionar () {
//Detect IE5.5+
version=0
if (navigator.appVersion.indexOf("MSIE")!=-1){
temp=navigator.appVersion.split("MSIE")
version=parseFloat(temp[1])
}

if (version>=5.5) //NON IE browser will return 0
alert("You're using IE5.5+")

alert("merda")

document.getElementById('cab').style.width = (document.body.clientWidth < 800) ? '780px': (document.body.clientWidth-5)+'px';
}