I wouldnt use Style attributes to specify width for tables. It can cause issues between browsers. The 1st table was easy, the 2nd table is a bit trickier. If you know the absolute width of the table you can code it like i did below. Hope this points you int the right direction.
nc_phpguy
<body>
<br><br>
<center>
why here the red TD's are indeed 1px wide
<table border="1" cellspacing="0" cellpadding="0" width="80%">
<tr>
<td width="1" bgcolor="red"><img src="/images_n/tp.gif" alt="" height="15" width="1"></td>
<td colspan="3" style="background-color:black;"><img src="/images_n/tp.gif" alt="" height="1" width="1"></td>
<td width="1" bgcolor="red"><img src="/images_n/tp.gif" alt="" height="1" width="1"></td>
</tr>
<tr>
<td colspan="2" style="background-color:black;"><img src="/images_n/tp.gif" alt="" height="15" width="1"></td>
<td style="background-color:aqua;"><img src="/images_n/tp.gif" alt="" height="1px" width="1"></td>
<td colspan="2" style="background-color:black;"><img src="/images_n/tp.gif" alt="" height="1" width="1"></td>
</tr>
</table>
<br><br>
why here the red TD's are NOT 1px wide
<table border="1" cellspacing="0" cellpadding="0" width="500">
<tr>
<td width="1" bgcolor="red"><img src="/images_n/tp.gif" alt="" height="15" width="1"></td>
<td style="background-color:black;" width="166"><img src="/images_n/tp.gif" alt="" height="1" width="1"></td>
<td style="background-color:black;" width="166"><img src="/images_n/tp.gif" alt="" height="1" width="1"></td>
<td style="background-color:black;" width="166"><img src="/images_n/tp.gif" alt="" height="1" width="1"></td>
<td width="1" bgcolor="red"><img src="/images_n/tp.gif" alt="" height="1" width="1"></td>
</tr>
<tr>
<td width="1" bgcolor="red"><img src="/images_n/tp.gif" alt="" height="15" width="1"></td>
<td colspan="3" style="background-color:black;"><img src="/images_n/tp.gif" alt="" height="1" width="1"></td>
<td width="1" bgcolor="red"><img src="/images_n/tp.gif" alt="" height="1" width="1"></td>
</tr>
<tr>
<td colspan="2" style="background-color:black;">a</td>
<td style="background-color:aqua;">b</td>
<td colspan="2" style="background-color:black;">c</td>
</tr>
</table>
</center>
</body>