"Drive-by downloads" can happen when you simply go to a webpage that is infected with malware embeded within an image or advertisement (Note: it is estimated that 1 out of every 1000 webpages, and about 70 out of the top 100 websites on the Web has malware images on it, or links to malware sites.) Products like AVG free will help to warn you only when you are searching by showing an indicator next to the search results. But if you pay for their "Complete Internet Security" it will help to protect you all the time you surf the web.
Many other security products that provide "complete internet security" will provide the same type of coverage as AVG.
Note: as stated in an earlier FAQs, the greatest protection to "drive by downloads" is to insure that you do not regularly surf the web using your Windows Administrator account, and that you keep your Windows software updated. For more information see:
Also note: that other products that are regularly used could have the need of being updated to avoid exploits (security holes) within that software. Some common examples might be:
- Adobe PDF software
- Adobe Flash
- Quick Time & iTunes
- Microsoft Office
- Microsoft Media Player