Variable number of columns in an HTML table

Question

The highlighted area is two columns that I would like to collapse into one.

<TABLE border="1" cellspacing="0" width="450px" cellpadding="3px" bordercolor="#FFFFFF">
        <TR>
                <TD rowspan="2" width="50px" height="50px" background="img/noimg75.png"></TD>
                <TD width="200px">1</TD>
                <TD width="200px">2</TD>
        </TR>
        <TR>
                <TD>3</TD>
                <TD>4</TD>
        </TR>
        <TR>
                <TD>5</TD>
                <TD>6</TD>
                <TD>7</TD>
        </TR>
</TABLE>

Answer 1

What's wrong with colspan?

<TABLE border="1" cellspacing="0" width="450px" cellpadding="3px" bordercolor="#FFFFFF">
    <TR>
        <TD rowspan="2" width="50px" height="50px" style="background:red;"></TD>
        <TD width="200px">1</TD>
        <TD width="200px">2</TD>
    </TR>
    <TR>
        <TD>3</TD>
        <TD>4</TD>
    </TR>
    <TR>
        <TD colspan="2">5 & 6</TD>
        <TD>7</TD>
    </TR>
</TABLE>

?

Demo: http://jsfiddle.net/9XU9x/

UPDATE per comments:

<TD colspan="2"><table border="2" width="100%"><tr><td width="50%">Five</td><td>Six</td></tr></table></TD>

New demo: http://jsfiddle.net/TzXaF/