Required checkbox on Paypal button?

I am creating a required checkbox on a Paypal button for a product. The checkbox is an agreement to have read the License agreement. I can do a simple one of these, for a button I add independently, but this has me lost. I would like the “Buy Now” button to not take you to Paypal for the purchase if the checkbox is not checked. I have the box in there like I lke it, but can’t get it to be required. I have read around here and quite a few other places, and nothing gets in depth enought for me to get this to work. Here is the code:

<table height=”100%” width=”100%” border=”0″ cellspacing=”0″ cellpadding=”0″>
<tr valign=”top” align=”center”>
<td>
<table id=”Table_01″ width=”550″ height=”470″ border=”0″ cellpadding=”0″ cellspacing=”0″>
<tr>
<td><object classid=”clsid?27CDB6E-AE6D-11cf-96B8-444553540000″ codebase=”http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=7,0,19,0” width=”550″ height=”115″>
<param name=”movie” value=”Products.swf”>
<param name=”quality” value=”high”>
<embed src=”Products.swf” quality=”high” pluginspage=”http://www.macromedia.com/go/getflashplayer” type=”application/x-shockwave-flash” width=”550″ height=”115″></embed>
</object></td>
</tr>
<tr>
<td><img src=”images/Products_02.gif” width=”550″ height=”405″></td>
</tr>
</table>

<script language=”javascript”>

function CalculateOrder(form)
{

if (form.os0.value == “1 User”)
form.amount.value = 795.00

if (form.os0.value == “2 Users”)
form.amount.value = 1490.00

if (form.os0.value == “3 Users”)
form.amount.value = 2085.00

if (form.os0.value == “Unlimited”)
form.amount.value = 5995.00

}

</script>

<div align=”center”>

<form target=”paypal” action=”https://www.paypal.com/cgi-bin/webscr” method=”post” >

<table>
<tr>
<td>
<font face=”Geometric 415 Medium BT” color=”#3D3D3D” size=”-1″>
<input type=”hidden” name=”on0″ value=”Licenses”>Number of Licenses</font>
</td>

<td>
<select name=”os0″>
<option value=”1 User” selected>1 User $795
<option value=”2 Users”>2 Users $1490
<option value=”3 Users”>3 Users $2085
<option value=”Unlimited”>Unlimited $5995
</select>
</td>

</tr>
</table>

<form>
<font face=”Geometric 415 Medium BT” color=”#3D3D3D” size=”-1″>
<input type=”checkbox” id=”agree” checked=”checked” value=”required”> I agree to the terms of the <a href=”http://www.turnaround-solutions.com/Agreement.html” target=”_blank”>License Agreement</a>.</font>

<br><br>
<form target=”paypal” action=”https://www.paypal.com/cgi-bin/webscr” method=”post”>
<input type=”image” src=”https://www.paypal.com/en_US/i/btn/x-click-but22.gif” border=”0″ name=”submit” onClick=”CalculateOrder(this.form)” alt=”Make payments with PayPal – it’s fast, free and secure!”>
<img alt=”” border=”0″ src=”https://www.paypal.com/en_US/i/scr/pixel.gif” width=”1″ height=”1″>
<input type=”hidden” name=”add” value=”1″>
<input type=”hidden” name=”cmd” value=”_cart”>
<input type=”hidden” name=”business” value=”[email protected]“>
<input type=”hidden” name=”item_name” value=”Turning Leads Into Move-Ins CD-ROM”>
<input type=”hidden” name=”amount” value=”1.00″>
<input type=”hidden” name=”no_note” value=”1″>
<input type=”hidden” name=”currency_code” value=”USD”>
<input type=”hidden” name=”bn” value=”PP-ShopCartBF”>
</form>

</div>

<font face=”Geometric 415 Medium BT” color=”#999999″ size=”-2″>
<br>Copyright © 2006 Turnaround Solutions, LLC. All rights reserved.</p>
<td align=”center” valign=”top”></td>
</tr>
</table>
<!– End ImageReady Slices –>
</body>
</html>

Any input on this would be very helpful, or if you need some more info or description, don’t hesitate to ask. Thanks folks.

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