function Rollover(cual,porcual, ext){
	if(document.images){
		document.images[cual].src = '/img/' + porcual + '.' + ext;
	}
}
function validate_email(field,alerttxt)
{
with (field)
{
apos=value.indexOf("@")
dotpos=value.lastIndexOf(".")
if (apos<1||dotpos-apos<2) 
  {alert(alerttxt);return false}
else {return true}
}
}