the form tag is in the worng place.
the code should be:
<p align="left" class="body3" style="margin: 0in 0in 0pt;"> <span class="body3" style="margin: 0in 0in 0pt;">
<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_xclick" />
</span>
<input type="hidden" name="bn" value="webassist.dreamweaver.4_5_0" />
<input type="hidden" name="business" value="terriweeding@msn.com" />
<input type="hidden" name="item_name" value="To Kill An Armchair Husband" />
<input type="hidden" name="amount" value="16.00" />
<input type="hidden" name="currency_code" value="USD" />
<input type="hidden" name="return" value="http://www.terriweeding.com/Thanks.html" />
<input type="hidden" name="cancel_return" value="http://www.terriweeding.com/Error.html" />
<input type="hidden" name="undefined_quantity" value="1" />
<input type="hidden" name="receiver_email" value="terriweeding@msn.com" />
<input type="hidden" name="mrb" value="R-3WH47588B4505740X" />
<input type="hidden" name="pal" value="ANNSXSLJLYR2A" />
<input type="hidden" name="no_shipping" value="0" />
<input type="hidden" name="no_note" value="0" />
<input type="image" name="submit" src="http://images.paypal.com/images/x-click-butcc.gif" border="0" alt="Make payments with PayPal, it's fast, free, and secure!" />
<p align="left"> </p>
</form></td>