function getStuff() {
	var aObj=document.getElementById('products').getElementsByTagName('input');
	for(var i=0; i<aObj.length; i++) {
		aObj[i].onkeyup=function() {Calc(aObj);};
		aObj[i].onclick=function() {if(this.value===this.defaultValue){this.value='';} };
	}
};
getStuff();

function Calc(aObj){
	var total = 0;
	
	var browserCheck = (document.all) ? 1 : 0;
	if(browserCheck>0) var classN = "className";
	else  var classN = "class";
	
	for(var i=0; i<aObj.length; i++) {
		if( (aObj[i].type == "text") && (aObj[i].name != "total")) {
			var prix = aObj[i].getAttribute(classN);
			var val = aObj[i].value;
			val = Number(val) * Number(prix);
			total = total + val;
		}
	}
	
	document.form1.total.value = total;
}