You can block those images and sites with Firefox or Mozilla as your browser (could probably be done with certain settings in Internet Explorer) or you could block those sites out completely with entries in your computer's "hosts" file. The downside to the "hosts" approach is that if the rat uses an IP address instead of a host name for loading the image you would have to rely on your browser to block the image. It's all pretty technical, but you can find sites out there that provide decent help with those kinds of settings.
I use firefox. the adblock feature would block the host I would think. Or you can use your firewall to block an ip adress if it's a static one.