function validate_form()
{

	var valid=true;
	
	var emailfilter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	var numberfilter = /^([0-9 ])+$/;
	
	if ( document.contactform.contactform_name.value == "" )
	{
		alert ( "Please fill in your name." );
		valid = false;
	}
	else if ( document.contactform.contactform_number.value == "" )
	{
		alert ( "Please fill in your phone number." );
		valid = false;
	}
	else if ( !numberfilter.test(document.contactform.contactform_number.value) || document.contactform.contactform_number.value.length < 8 )
	{
		alert ( "Please enter a valid phone number." );
		valid = false;
	}
	else if ( document.contactform.contactform_email.value == "" )
	{
		alert ( "Please fill in your email address." );
		valid = false;
	}
	else if ( !emailfilter.test(document.contactform.contactform_email.value) )
	{
		alert ( "Please enter a valid email address." );
		valid = false;
	}
//	else if ( document.contactform.contactform_duration.selectedIndex == 0 )
//	{
//		alert ( "Please select the duration." );
//		valid = false;
//	}

	return valid;
}

function  empty_field(field)
{
	if (field.value == field.defaultValue)
	{
		field.value = "";
	}
}