In Internet Explorer, that's done by selecting Tools | Show Related Links. As the name directly implies, related links are links that are related to the page you are currently viewing. For example, if you were viewing this website and clicked Tools | Show Related Links, a sidebar to the left of the browser window would appear and that sidebar would display links for other antivirus related websites.
In short, there is nothing hidden, surreptitous, or deceitful about related.htm and it's not even enabled by default. You have to choose it to use it. Conversely, spyware, as its name implies, is software that monitors without the user's consent and most especially without their knowledge.
Related.htm is nothing more than a semi-useful feature that's there if you need it, that somehow got caught in the crosshairs of overzealous spyware scanners.
