Web Security Guard is a free software that prevents you from accidentally visiting malicious websites. Web Security Guard has a huge database of websites, and the threat level they pose. When you try to visit a website that has some problems associated with it, Web Security Guard will show you warning about that website before you navigate to the website. You can read the website report about that website, and what other users have said about it, and then decide whether you still want to visit that website.
Web Security Guard also integrates with your search results. So, if you search for something in the popular search engines, Web Security Guard will show you safety rating of each website in the search result. This way you know which link can be dangerous to click. Another free similar software that you can try is AVG LinkScanner that comes from the house of AVG Free Antivirus.
Web Security Guard keeps itself updated automatically. You can even schedule the database update to happen automatically. This simple free software ensures that you do not end up accidentally visiting a malicious website, and get some adware or malware installed on your computer. Of course, it is still a good idea to have some anti-adware and anti-malware on your computer, like, Ad-Aware and Spybot Search & Destroy.