Remove all of the sites from your computer's "favorites" list or bookmarks. If they are not easily accessible, you'll be less likely to check them.
Block the sites. You can do this by going to "Tools," "Internet Options," "Content" and then "Content Advisor." Press "Enable," and then go to "Approved Sites." Add the site and then press "Never." Since this is a multi-step process, you are less likely to remove it to regain access.
Fill the void. Add interesting blogs and news sites to your bookmarks to read. Blogs are quite similar to gossip in that you're looking into someone's life, but less intrusive than gossip sites.
Find something else to do when gossip shows are on television. Transform your former TV viewing hour or gossip site browsing time into your reading hour or cleaning hour or go-to-the-gym hour. There are many productive things that you can do rather than browsing the gossip blogs!
Get rid of past issues of gossip magazines and stop all subscriptions. If it's not lying around, you can't read it. Subscribe to news-related magazines or magazines that pertain to your favorite hobby. It'll give you something to do and something more intellectually stimulating to talk about.
Change the subject. If people are talking about celebrity trash, veer the conversation in a new direction. After all, with all your new interests and free time, you'll have more to talk about.
Don't feel badly about slipping up once in a while. Gossip is everywhere. Nowadays it's considered legitimate news. If you find yourself sneaking a peek just remember that a little is okay but when it becomes a daily habit or obsession that gets in the way of "real" things then it's a problem.