Form Calculator - How To Insert New Selection

I am working on inserting a new selection into a form which uses Javascript to calculate totals. Here is the code for the top of the page:

Code:
<script type="text/javascript">
<!--
function MM_findObj(n, d) { //v4.01
var p,i,x; if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
if(!x && d.getElementById) x=d.getElementById(n); return x;
}function KW_getVal(o){ //v1.2 .....

Here is the code contained within the form:
Code:
<tr><td><span class="item_title"Logo Sticker</span> (min. order 100) <img src="images/0_pic.gif" border="0" onclick="MM_openBrWindow('images/orderform/ogo_sticker.gif','','scrollbars=yes,resizable=yes,width=400,height=550')" /> </td>
<td width="178">$4.00<br />per 100</td>
<td ><select name="Logo_Decals_MEMB_A0_006" id="cpa_logo_stickers" onchange="Calc(this.form);">
<option value="0"> </option>
<option value="100">100</option> .....
I know that this is not the proper code, it is copied from another form that uses a different Javascript. What code would I need to insert to make it work here?

I have a sample of working code that is used for an item which costs $1.00 and has no drop down selector:
Code:
<tr>
<td><span class="item_title-blue">Envelope - Individual</span> <img src="images/0_pic.gif" alt="Click to See Picture of Item" border="0" onclick="MM_openBrWindow('images/orderform/env.jpg','','scrollbars=yes,resizable=yes,width=408,height=547')" /></td>
<td align="center" valign="middle">$1.00 </td>
<td align="center" ><p>
<input name="Envelope" type="text" id="FormsEditField224" onchange="KW_calcForm('Envelope Total',100,2,'#Envelope','*','1')" value="" size="4" maxlength="4" />
<label><div align="left">
</label></td><td align="center"><p>
<input id="FormsEditField225" type="text" name="Envelope Total" value="" size="9" maxlength="10" onfocus="this.blur()"/>
</p></td></tr><tr>

The above code does run correctly, I just need it to be for a 4.00 per 100 drop down list as demonstrated before.