AOL has always lagged in providing software for Macs, so I use Aladdin's Internet Clean-up (with Spy Alert) [sounds like an SNL skit -- "It's a floor cleaner AND a dessert topping!!"] for the same purpose.
PCers not on AOL should immediately go to
www.komando.com and do free downloads of programs to deal with spyware and adware. If you need a primer on spyware, use that as a search term on that site. Kim (Komando) has written many columns about it.
Mike's right, the huge amount of garbage that is eating up space on your hard disk, and slowing everything to a crawl, is mind-boggling. But even after you install the protective software, you have to exercise diligence and vigilance in running it with some frequency.
(For anyone not yet paranoid enough, spyware does lots of nasty little things, such as watching where you go on the net, which pages of a site you dwell on (that would be Miss July for some), and even the precise keystrokes you made during a session, so that all your emails, chat notes, and IMs are readable. If you can't believe such a thing could already be on your computer, it almost certainly is. But, then, it's always something.)