var theImagesC = new Array()

theImagesC[0] = 'thumbs/c1.gif'
theImagesC[1] = 'thumbs/c2.gif'
theImagesC[2] = 'thumbs/c3.gif'
theImagesC[3] = 'thumbs/c4.gif'
theImagesC[4] = 'thumbs/c5.gif'
theImagesC[5] = 'thumbs/c6.gif'
theImagesC[6] = 'thumbs/c7.gif'

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