function CheckLight()
{
document.UserData.Extra.value = navigator.appName + ", " + navigator.userAgent;
document.UserData.Lxone.value = screen.width;
document.UserData.Lxtwo.value = screen.height;
if (navigator.appName == "Netscape")
{
  document.UserData.Lxthr.value = window.outerWidth;
  document.UserData.Lxfou.value = window.outerHeight;
}
}

function CheckForm()
{
document.UserData.Extra.value = navigator.appName + ", " + navigator.userAgent;
document.UserData.Lxone.value = screen.width;
document.UserData.Lxtwo.value = screen.height;

if (navigator.appName == "Netscape")
{
  document.UserData.Lxthr.value = window.outerWidth;
  document.UserData.Lxfou.value = window.outerHeight;
}

var Email = document.UserData.email.value;

if(document.UserData.firstname.value == '' || document.UserData.firstname.value.length == 1)
{
  document.UserData.firstname.focus();
  alert("Please enter your first name.");
  return false;
}

if(document.UserData.lastname.value == '' || document.UserData.lastname.value.length == 1)
{
  document.UserData.lastname.focus();
  alert("Please enter your last name.");
  return false;
}

if(Email == '')
{
  document.UserData.email.focus();
  alert("Please enter your email address\nor call us, if you do not have one.");
  return false;
}

if(Email.indexOf('@') < 1 || Email.indexOf('.') < 1 || Email.length < 5)
{
  document.UserData.email.focus();
  alert("Sorry,\n'"+ Email +"' does not look like a valid email address.\n\nPlease enter your email address\nor call us, if you do not have one.");
  return false;
}

if(Email.indexOf('@.') != -1 || Email.indexOf('.@') != -1)
{
  document.UserData.email.focus();
  alert("Sorry,\n'"+ Email +"' does not look like a valid email address.\n\nPlease enter your email address\nor call us, if you do not have one.");
  return false;
}

if(document.UserData.postal.value.length < 10)
{
  document.UserData.postal.focus();
  alert("Please enter at least your city and country.");
  return false;
}
}