Вот так работает и в IE, и в Opera:
<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0>
<TR height="431">
<TD style="background: url(pics/bg1.jpg);"></TD>
<TD style="background: url(pics/bg2.jpg);"></TD>
</TR>
<TR height="431">
<TD style="background: url(pics/bg3.jpg);"></TD>
<TD style="background: url(pics/bg4.jpg);"></TD>
</TR>
</table>