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.required_name) )
        {
        alert("Please enter your name.");
        F.required_name.focus();
        }
    else 
    if ( IsEmpty(F.required_company) )
        {
        alert("Please enter your company's name.");
        F.required_company.focus();
        }
   else 
    if ( IsEmpty(F.required_voicearea) )
        {
        alert("Please enter your voice phone's area code.");
        F.required_voicearea.focus();
        }
    else 
    if ( IsEmpty(F.required_voicephone) )
        {
        alert("Please enter your voice phone number.");
        F.required_voicephone.focus();
        }
    else 
    if ( IsEmpty(F.required_email) || !IsEmail(F.required_email) )
        {
        alert("Please enter a valid e-mail address.");
        F.required_email.focus();
        }
    else 
        return( true );
    
    return( false );
}