If you venture into the dark alleys of the Internet, prepare to be mugged. Criminals will try to lure you in with offers of free porn, cracked software downloads, or free music or movies. According to McAfee, “free downloads” are the most virus-prone search term. Then, when you visit the site, or download the files, bad things happen. It'll cost you more to have your computer cleaned than you saved by vising these sites, and if you did it at work, you might also get fired.