You can use the following HTML-Code as well:
<a href="http://www.seat-event.info/" target="_blank"><img src="http://www.seat-leon.de/banner/speyer2007.jpg" width="468" height="60" border="0" alt="seat-leon.de event 2007 at Speyer" title="seat-leon.de event 2007 at Speyer"></a>

or this BB-Code for your web board signature:
[CENTER][URL="http://www.seat-event.info/"][IMG]http://www.seat-leon.de/banner/speyer2007.jpg[/IMG][/URL][/CENTER]