var aryImages = new Array(2);

aryImages[0] = "images/experts/service/ex-service00.gif";
aryImages[1] = "images/experts/service/ex-service01.gif";
aryImages[2] = "images/experts/service/ex-service02.gif";
aryImages[3] = "images/experts/service/ex-service03.gif";
aryImages[4] = "images/experts/service/ex-service04.gif";
aryImages[5] = "images/experts/service/ex-service05.gif";
aryImages[6] = "images/experts/service/ex-service06.gif";
aryImages[7] = "images/experts/service/ex-service07.gif";
aryImages[8] = "images/experts/service/ex-service08.gif";
aryImages[9] = "images/experts/service/ex-service09.gif";
aryImages[10] = "images/experts/service/ex-service10.gif";
aryImages[11] = "images/experts/service/ex-service11.gif";
aryImages[12] = "images/experts/service/ex-service12.gif";
aryImages[13] = "images/experts/service/ex-service13.gif";
aryImages[14] = "images/experts/service/ex-service14.gif";
aryImages[15] = "images/experts/service/ex-service15.gif";
aryImages[16] = "images/experts/service/ex-service16.gif";
      

for (i=0; i < aryImages.length; i++) {
  var preload = new Image();
  preload.src = aryImages[i];
}

function swap(imgIndex) {
  document['imgMain'].src = aryImages[imgIndex];
}