No need to give up...you'll never understand this cart if you do that
Try this...open up common.js and add this to the very bottom:
function MM_openBrWindow(theURL,winName,features) { //v2.0
window.open(theURL,winName,features);
}
Then see if your pop-up link works. The image may not load, but see if you at least get the pop-up.