Don't try this at home--not if you want to have a working computer. Search for "Free Screensavers," we're told, and 64% of the sites you'll find are the kinds that can gum up your machine with spyware or a computer virus. A team of researchers, let by Ben Edelman and Hannah Rosenbaum of a British firm called Site Advisor, tried entering 1,394 popular search terms into the web's most popular search engines--Google, Yahoo!, MSN, AOL and Ask.com. They came up with a chart you may find both amusing and sobering. Even if you search for something as harmless as "I...