function validate(contactForm) 
{

    var strMsg = "";
    if  (!isNaN(contactForm.first_name.value))
    {
        strMsg = strMsg + "\n" + "Please enter your first name.";
    }

    if  (!isNaN(contactForm.last_name.value))
    {
        strMsg = strMsg + "\n" + "Please enter your last name.";
    }

    if  (!isNaN(contactForm.company.value))
    {
        strMsg = strMsg + "\n" + "Please enter your company name.";
    }

    if  (!isNaN(contactForm.email.value))
    {
        strMsg = strMsg + "\n" + "Please enter your e-mail address.";
    }

    if  (!isNaN(contactForm.comments.value))
    {
        strMsg = strMsg + "\n" + "Please enter your questions/comments.";
    }

    if (strMsg != "")
    {
        alert(strMsg);
        return false;
    }

contactForm.submit();
    return true;
}