If your anti-virus program raises an alert when surfing or downloading a file from the Internet then your computer has already been infected or was about to be infected when your anti-virus software intercepted the online threat. As you may know you should always run a full system scan after any reported infection attempts as best practice; Webroot anti-virus for example reminds advises its user automatically to so.
To reduce the risks of so called drive-by downloads when browsing the Web Webroot Antivirus with Antispyware, Norton 360, Norton Internet Security 2010 as well as AVG Anti-Virus 9.0 Free Edition for example have an integrated URL or Link Scanner which prevents users from visiting sites containing malware and phishing sites. Computers having only traditional anti-virus capabilities which lack a real-time link scan feature such as AVG LinkScanner Active Surf-Shield can have their security beefed up by downloading and installing AVG LinkScanner at absolutely no cost or obligation.
Yet, the AVG LinkScanner has more to protect you: AVG LinkScanner Search-Shield technology adds a security rating to the result of your favourite Search Engine (Yahoo, Google, Bing) results so that you probably won’t even click dangerous links, and which point Active Surf-Shield would kick in anyway. Conversely, it possible running AVG LinkScanner only with passive protection by selecting custom selection as install option and deactivating LinkScanner® Active Surf-Shield.