var nav = (document.layers) ? true : false;
var iex = (document.all) ? true : false;
var ff = document.getElementById? true : false;

<!-- Don t let the next 2 statements wrap... They must be one line each, otherwise they will not run, and yo will get javascript errors --> 
if(iex || ff) 
	document.write('<a href="http://www.rockoalmenar.com" target="_blank" id="promoDir"><img src="img/patrocinadors/clubesportiurockoalmenar.gif" border=0 name="banner" id="banner" /></a>')

if(nav) 
	document.write('<a href="" onClick="clickLink(); return false;" onMouseOver="descript(); return true;" onmouseout="nothing()" id="promoDir"><img src="img/patrocinadors/clubesportiurockoalmenar.gif" border=0 name="banner" width="468" height="60"></a>')