if (document.images)
{
  pic1= new Image(50,100); 
  pic1.src="http://www.inneractive.nl/images/buttons/prev.gif"; 

  pic2= new Image(50,100); 
  pic2.src="http://www.inneractive.nl/images/buttons/prev-over.gif"; 

  pic3= new Image(50,100); 
  pic3.src="http://www.inneractive.nl/images/buttons/next.gif"; 
  
  pic4= new Image(50,100); 
  pic4.src="http://www.inneractive.nl/images/buttons/next-over.gif"; 
}

<!--
function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}
//-->