var menu_cache = new Object();
function menu_over(id)
{
if (typeof menu_cache[id] == "undefined")
 menu_cache[id] = document.getElementById('mp'+id).src;

document.getElementById('mp'+id).src = '/images/kat_'+id+'_ger_over.jpg'; 
}

function menu_out(id)
{
if (typeof menu_cache[id] != "undefined")
 document.getElementById('mp'+id).src = menu_cache[id]; 
}