var theImagesA = new Array()

theImagesA[0] = 'thumbs/a1.GIF'
theImagesA[1] = 'thumbs/a2.GIF'
theImagesA[2] = 'thumbs/a3.GIF'
theImagesA[3] = 'thumbs/a4.GIF'
theImagesA[4] = 'thumbs/a5.GIF'
theImagesA[5] = 'thumbs/a6.GIF'
theImagesA[6] = 'thumbs/a7.GIF'

var j = 0
var p = theImagesA.length;
var preBuffer = new Array()
for (i = 0; i < p; i++){
   preBuffer[i] = new Image()
   preBuffer[i].src = theImagesA[i]
}
var whichImageA = Math.round(Math.random()*(p-1));
function showImageA(){
document.write('<img src="'+theImagesA[whichImageA]+'">');
}