problem centering Menu - control inside a td

[Jeff]

ASP.NET 3.5

I have a menu control on my webpage, which I want to be horizontally
centered. That is no problem in IE6 and IE7. But when testing in Opera (
version 9), the menu control isn't centered, it is alligned to the left.

<td colspan="3" style="background-color:Blue; text-align:center;">
<mb:Menu ID="Menu1" runat="server" />
</td>

So I tryed to add the align property and a div, but that didn't help
either...:

<td colspan="3" style="background-color:Blue; text-align:center;"
align="center">
<div style="margin-left:auto; margin-right:auto;">
<mb:Menu ID="Menu1" runat="server" />
</div>
</td>

any suggestions?