MSFPhover = 
  (((navigator.appName == "Netscape") && 
  (parseInt(navigator.appVersion) >= 3 )) || 
  ((navigator.appName == "Microsoft Internet Explorer") && 
  (parseInt(navigator.appVersion) >= 4 ))); 
function MSFPpreload(img) 
{
  var a=new Image(); a.src=img; return a; 
}
if(MSFPhover) { MSFPnav1n=MSFPpreload("topmenu_hauptmenue.gif"); MSFPnav1h=MSFPpreload("topmenu_hauptmenue2.gif"); }
if(MSFPhover) { MSFPnav2n=MSFPpreload("topmenu_buero.gif"); MSFPnav2h=MSFPpreload("topmenu_buero2.gif"); }
if(MSFPhover) { MSFPnav3n=MSFPpreload("topmenu_referenzen.gif"); MSFPnav3h=MSFPpreload("topmenu_referenzen2.gif"); }
if(MSFPhover) { MSFPnav4n=MSFPpreload("topmenu_kontakt.gif"); MSFPnav4h=MSFPpreload("topmenu_kontakt2.gif"); }
if(MSFPhover) { MSFPnav5n=MSFPpreload("topmenu_anfahrt.gif"); MSFPnav5h=MSFPpreload("topmenu_anfahrt2.gif"); }