Most people lock their doors and windows, use a paper shredder to protect themselves from identity theft, and install antivirus software on their computers. Yet they routinely surf the Internet without giving a second thought to whether their browser is secure and their personal information safe. Unfortunately, it's easy for someone with nefarious intentions to use a Web site to glean data from -- or introduce spyware to -- your computer. Even worse, sometimes all you have to do is randomly click on a site to have your data probed in a most unwelcome way.