I'm, using CSS clipped bgs.
put the hover and non-hover image above each other in a single image file, then slide the bg up/down using css to show the right bit.
See my tabs:
www.alpha-matrix-design.co.uk
are made with this image:
using this HTML:
[code:1:bd2facf9f0]<ul id="mainmenu" class="menu">
<li><a class="left_current">Home</a></li>
<li><a class="mid" href="?section=portfolio">Portfolio</a></li>
<li><a class="mid" href="?section=contact">Contact</a></li>
<li><a class="right" href="?section=login">Client Log-in</a></li>
</ul>[/code:1:bd2facf9f0]
and this CSS:
www.alpha-matrix-design.co.uk/css/tabs.css