To keep its growth moving, Google (NASDAQ:GOOG) needs to target billion-dollar market opportunities. So why not make a play for security? Not only is it a massive market, it's still growing at a healthy pace. Thus, it was no surprise last week when we learned the mega-search giant had bought security firm GreenBorder Technologies.

Privately held GreenBorder has software that allows you to set up a virtual computer to surf the Web. If there is a virus or malware attack, you can simply turn off the virtual instance, ensuring that your main computer remains safe.

It's an ingenious system, and it means there's no need to continue to update security systems with new signatures and patches. 

Google has provided no details on its intentions for GreenBorder. Yet it's logical that it could be a core piece of its growing suite of applications, such as email, spreadsheets, word processors, and calendars.

"Google is always looking to fill gaps in the Internet user's experience, and if it can shove a thumb in Microsoft's (NASDAQ:MSFT) eye in the process, all the better," 451 Group analyst Nick Selby recently told me. "By offering secure browsing with GreenBorder's agent, Google can make a strong pitch to small businesses and enterprises fearful of Web-born threats like worms, spyware and the like."

This could be part of an even broader strategy of attacking the cash cows of Symantec (NASDAQ:SYMC), McAfee (NASDAQ:MFE), and Trend Micro (NASDAQ:TMIC). While I think this has some logic to it, Google has a lot on its plate. It must integrate DoubleClick as well as build on its acquisition of YouTube.

If Google really does have its sights set on being a big player in security, it's going to take a while. So in the meantime, I think the main players should feel secure ... but they need to keep a watchful eye on the giant.

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Microsoft and Symantec are Motley Fool Inside Value picks.

Fool contributor Tom Taulli, author of The Complete M&A Handbook, does not own shares mentioned in this article. He is currently ranked 1,161 out of 29,574 in CAPS. The Fool has a disclosure policy.