var theImagesG = new Array()

theImagesG[0] = 'thumbs/G1.gif'
theImagesG[1] = 'thumbs/G2.gif'
theImagesG[2] = 'thumbs/G3.gif'
theImagesG[3] = 'thumbs/G4.gif'
theImagesG[4] = 'thumbs/G5.gif'
theImagesG[5] = 'thumbs/G6.gif'
theImagesG[6] = 'thumbs/G7.gif'

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