You can't style the width on an A tag (IE's behaviour is incorrect).
I'd markup you menu in a unordered list, something like:
<ul>
<li><a href="http://www.beolens.co.uk/photography/">Home</a></li>
<li><a href="http://www.beolens.co.uk/photography/landscapes/">Landscape</a></li>
<li><a href="http://www.beolens.co.uk/photography/birds/">Birds</a></li>
<li><a href="http://www.beolens.co.uk/photography/mammals/">Mammals</a></li>
<li><a href="http://www.beolens.co.uk/photography/insects/">Insects</a></li>
<li><a href="http://www.beolens.co.uk/photography/plants/">Plants</a></li>
<li><a href="http://www.beolens.co.uk/photography/people/">People</a></li>
<li><a href="http://www.beolens.co.uk/photography/misc/">Miscellaneous</a></li>
<li><a href="#">Prints</a></li>
</ul>
Then style the list something like:
#topmenu ul li {
float:left;
width:5em;
list-style:none;
padding:2px;
}
Of course there's many ways to skin a cat so anything whereby you don't style the A tag's width will probably work.
Hope that helps. Haven't tried it but it should be along the right lines.
One tip, always develop in Firefox first then test in IE. Firefox is much more standard compliant so if you get something to work there it'll more likely work in IE. IE has a lot of proprietry features that muddy the water.
BTW, nice site!
