All outgoing links should open in a new window, while internal links open in the same window. From a webmasters perspective, you really don’t want people to navigate away from your site with no way to find it again which is what will happen if you keep affiliate links opening in the same window, and the user didn’t like what he saw with that particular gambling site. From a users standpoint, there have been many times that I got annoyed because I found exactly what I was looking for on a website, clicked on one of their affiliate links that opened in the same window, and after navigating at the new site and not liking the product, I could not find my way back to the information I wanted from the original site, so both I and the site owner missed out. This is a no brainer, outgoing links in new window, internal links same window.