If you want the truth is virus scans, “malwarebytes” and “Superantispyware” are two of the best (and free) utilities. If you can avoid it, don’t ever go to Google and randomly enter sites discussing viruses or offering “system scans”, etc.. On this topic, only go to trusted, reputable sites (Microsoft, Yahoo, Malwarebytes.org, etc.). Another great idea is to install an “add-on” to your browser, such as “no script” available for Firefox. It prevents scripts from running through your browser unless or until you “allow” it. This add-on definitely gives you an added layer of protection when site-hopping.
What kind of bad things can they do with scripts?