function CheckFields(form)
{
	var EmptyFieldsForUser	= new Array();
	var FormFields			= form.elements;
	for (var i = 0; i < FormFields.length; i++) {
		if (FormFields[i].id.indexOf('Check') > -1 && FormFields[i].value == "")
		{
			EmptyFieldsForUser.push(FormFields[i].id.substr(5));
		}
	}
	if(EmptyFieldsForUser.length==0)
	{
		return true;
	}else
	{
		var EmptyMessageContainer	= document.getElementById('EmptyMessage');
		if(EmptyMessageContainer)
		{
			EmptyMessageContainer.innerText		= 'Вы не заполнили поля: ';
			for (var i = 0; i < EmptyFieldsForUser.length; i++) {
				EmptyMessageContainer.innerText	= EmptyMessageContainer.innerText	 + EmptyFieldsForUser[i] + '; ';
			}
			EmptyMessageContainer.innerText		= EmptyMessageContainer.innerText.substr(0, EmptyMessageContainer.innerText.length -2) + '.';
		}
		return false;
	}
}
 
 
<form action="SendOrder" method="post" enctype="multipart/form-data" name="OrderFields" lang="ru" onsubmit="return CheckFields(this);">
<table>
	<tr>
    	<td colspan="3"><div id="EmptyMessage"></div></td>
    </tr> 
    <tr align="left">
        <td><input name="NameCustomer" type="text" id="CheckИмя" /></td> <td><b>Имя</b></td>   <td width="25px" rowspan="6" class="TextTopCenter"><b>Жирным выделены обязательные поля.</b></td>
 
    </tr>
    <tr align="left">
        <td><input name="SurNameCustomer" type="text" id="CheckФамилия" /></td> <td>Фамилия</td>
 
    </tr>
    <tr align="left">
        <td><input name="FatherNameCustomer" type="text" /> </td><td>Отчество</td>
    </tr>
    <tr align="left">
        <td><input name="TelephoneCustomer" type="text" /></td> <td>Контактный телефон</td>
    </tr>
    <tr align="left">
        <td>
        <input name="EmailCustomer" type="text" id="CheckE-mail" /></td><td> <b>E-mail</b></td>
    </tr>
    <tr>
        <td colspan="2">
        <b>Сообщение</b>
        <textarea name="OrderText" class="TextAreaForOrder" id="CheckСообщение"></textarea>
        </td>
    </tr>
    <tr>
        <td colspan="2">
       <input name="submit" type="submit" />
        </td>
    </tr>
</table>
</form>