function validate_required(field,alerttxt)
{
with (field)
{
if (value==null||value=="")
  {alert(alerttxt);return false;}
else {return true}
}
}

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;}
}
}

function validate_contact_form(thisform)
{
with (thisform)
{
if (validate_email(email,"Not a valid e-mail address!")==false)
  {email.focus();return false;}
if (validate_required(email,"Email must be filled out!")==false)
  {email.focus();return false;}
if (validate_required(firstname,"Name must be filled out!")==false)
  {firstname.focus();return false;}
if (validate_required(lastname,"Name must be filled out!")==false)
  {lastname.focus();return false;}
}
}