Know your enemies. If Microsoft (NASDAQ:MSFT) were to jot down the names of companies that could unseat it, the list would be awfully short. And the hit men gunning for Microsoft would need to be sharpshooters -- because knocking off Mr. Softy is a long shot.

So who could challenge the software king? Apple Computer (NASDAQ:AAPL)? Apple has class and momentum, but it's still way behind in market share. Oracle (NASDAQ:ORCL)? You have to admire Larry Ellison's spunk, but bravado alone won't topple Microsoft as the world's leading software giant.

What about Google (NASDAQ:GOOG)? Sure, you've never seen Microsoft and Google duke it out, I gather. Ellison and Steve Jobs have no problem dissing Microsoft in public, and an attack by a kinder, gentler Google would surely be a case of friendly fire. Right?

Well, let's see. This week, Google launched software for its new video-streaming subdomain. Folks have been downloading a free video viewer from Google since Monday. Then yesterday, Tim Beyers looked at how the beta of Google Video has landed the company in hot water when it comes to copyright infringements.

Microsoft doesn't appear threatened by Google's newest foray at the moment. Multimedia players like Microsoft's Media Player and RealNetworks' (NASDAQ:RNWK) RealPlayer are broad applications. Google's viewer is just for Google's own video library. Then again, little snowballs can grow pretty big once they start rolling down the hill.

Everywhere Microsoft turns, it seems as if Google is in its way. Google has had no problem populating the Web with Mozilla's Firefox browser as an alternative to Microsoft's leading Internet Explorer. At the very least, it has been pushing to get users to tack on Google's toolbar to Microsoft's browser. Google's Gmail is looking to unseat Yahoo! (NASDAQ:YHOO) and Microsoft's Hotmail from the email throne. And Google's desktop search feature is hoping to supplant the search function of Windows.

Everywhere you look, Google seems to be planting the seeds whose flowers may one day provide the thorns in Microsoft's side.

Read up on the Google quickie revolution:

Longtime Fool contributor Rick Munarriz wouldn't take on Microsoft or Google in the boxing ring, though he's not above throwing a quick sucker punch in their direction before running the other way. He does not own shares in any of the companies mentioned in this story. The Fool has a disclosure policy. Rick is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early.