if (document.images) {

   aout = new Image();
   aout.src = "images/btn_home.gif";
   bout = new Image();
   bout.src = "images/btn_aboutus.gif";
   cout = new Image();
   cout.src = "images/btn_ourcoaches.gif";
   dout = new Image();
   dout.src = "images/btn_generalcharter.gif";
   eout = new Image();
   eout.src = "images/btn_schoolcharter.gif";
   fout = new Image();
   fout.src = "images/btn_timetables.gif";
   gout = new Image();
   gout.src = "images/btn_kewtoorak.gif";
   hout = new Image();
   hout.src = "images/btn_contactus.gif";
   iout = new Image();
   iout.src = "images/btn_links.gif";
   kout = new Image();
   kout.src = "images/btn_login.gif";
   jout = new Image();
   jout.src = "images/btn_quote.gif";
   lout = new Image();
   lout.src = "images/btn_safety.gif";

   ain = new Image();
   ain.src = "images/btn_home_on.gif";
   bin = new Image();
   bin.src = "images/btn_aboutus_on.gif";
   cin = new Image();
   cin.src = "images/btn_ourcoaches_on.gif";
   din = new Image();
   din.src = "images/btn_generalcharter_on.gif";
   ein = new Image();
   ein.src = "images/btn_schoolcharter_on.gif";
   fin = new Image();
   fin.src = "images/btn_timetables_on.gif";
   gin = new Image();
   gin.src = "images/btn_kewtoorak_on.gif";
   hin = new Image();
   hin.src = "images/btn_contactus_on.gif";
   iin = new Image();
   iin.src = "images/btn_links_on.gif";
   kin = new Image();
   kin.src = "images/btn_login_on.gif";
   jin = new Image();
   jin.src = "images/btn_quote_on.gif";
   lin = new Image();
   lin.src = "images/btn_safety_on.gif";
}

// Image Swapping functions

function imgOn(imgName) {
   if (document.images) {
       document[imgName].src = eval(imgName + "in.src");
       }
}

function imgOff(imgName) {

   if (document.images)  {
       document[imgName].src = eval(imgName + "out.src");  
       }
}