function IsEmpty( text )
{
    if( text.value.length == 0 ) 
        return( true );
    for( var i=0; i<text.value.length; ++i )  
    {
        var ch = text.value.charAt(i);
        if( ch != ' ' && ch != '\t' ) 
            return( false );
    }
    return( true );
}


function IsEmail( text )
{
    if( text.value.length == 0 ) 
        return( false );
    if( text.value.indexOf("@") == -1 || text.value.indexOf(".") == -1 )
        return( false );
    return( true );
}


function ValidateContactForm(F)
{
    if ( IsEmpty(F.txtFirstName) )
        {
        alert("Please enter your first name.");
        F.txtFirstName.focus();
        }
    else 
	 if ( IsEmpty(F.txtLastName) )
        {
        alert("Please enter your last name.");
        F.txtLastName.focus();
        }
    else 
   if ( IsEmpty(F.txtCity) )
        {
        alert("Please enter your city.");
        F.txtCity.focus();
        }
    else 
   if ( IsEmpty(F.txtState) )
        {
        alert("Please enter your state.");
        F.txtState.focus();
        }
    else 
   if ( IsEmpty(F.txtZip) )
        {
        alert("Please enter your zip code.");
        F.txtZip.focus();
        }
    else 
    if ( IsEmpty(F.txtEmail) || !IsEmail(F.txtEmail) )
        {
        alert("Please enter a valid e-mail address.");
        F.txtEmail.focus();
        }
    else 
        return( true );
    
    return( false );
}