Hey All, I have a form that I need 2 inputs to be mandatory before the mail gets sent. (the name and email)

Here is the form code.
Code:
<form id="FormTB" action="">
<input type="hidden" id="Form_ID" name="Form_ID"  value="<?php echo $eid; ?>" />
<center><strong>Request a Quote</strong></center><br />
<table width="100%">
<tr>
<td width="30%">*Your Name:</td><td width="20%">&nbsp;</td><td width="50%"><input type="text" id="Form_Name" name="Form_Name" /></td>
</tr>
<tr>
<td width="30%">Company Name:</td><td width="20%">&nbsp;</td><td width="50%"><input type="text" id="Form_Company" name="Form_Company" /></td>
</tr>

<tr>
<td>*Your E-Mail:</td><td>&nbsp;</td><td><input type="text" id="Form_Email" name="Form_Email" /></td>
</tr>
<tr>
<td width="30%">*Phone Number:</td><td width="20%">&nbsp;</td><td width="50%"><input type="text" id="Form_Number" name="Form_Number" /></td>
</tr>
<tr><td colspan="3">&nbsp;</td></tr>
<tr>
<td width="100%" align="center" colspan="3">
<input type="button" class="button" name="Form_Submit" value="Request Quote" />
</td>
</tr>
<tr><td colspan="3">&nbsp;</td></tr>
<tr>
<td width="100%">
<b><?php echo $name; ?></b><br />
<b>Manufacturer:</b> #<?php echo $manu;?><br />
 <b>Model#:</b> <?php echo $model;?><br />
  <b>Category:</b> <?php echo $Category;?><br />
  </td>
</tr>
</table>
</form>
And here is the JS that I am using with it.
Code:
<script language="javascript" type="text/javascript">
$(function() {  
  $(".button").click(function() {  
  var name = $("#Form_Name").val();
  var email = $("#Form_Email").val();
  var eid = $("#Form_ID").val();
   var company = $("#Form_Company").val();
    var number = $("#Form_Number").val();
    var dataString = 'name='+ name + '&email=' + email + '&eid=' + eid + '&Company=' + company + '&Number=' + number;    
//alert (dataString);return false;  
		$.ajax({  
		  type: "POST",  
		  url: "AJAX_Quote.php",
		  data: dataString,  
		  success: function() {  
			tb_remove();
			setTimeout("Thanks()", 450);
		  }  
		});   
	});  
});  
function Thanks()
{
tb_show('Thank You', '#TB_inline?width=400&height=400&inlineId=TBThanks&modal=false', false);
}
jQuery.noConflict(); 
function clearText(field){

    if (field.defaultValue == field.value) field.value = '';
    else if (field.value == '') field.value = field.defaultValue;

}
</script>
I know you have to add something like

Code:
/* validate function returns true if "ok" false if "bad" */
  validate = function(){
     /* Check if it is blank */
     if (document.getElementById('Form_Name').value = ''){
       alert('You must enter a First Name!');
       return false;
     }
     return true;

  }
But not quite sure how to do it. Can I just add that code to my existing JS or do I have to completely redo it?

Any help would be appreciated.

Thanks