Microsoft may want to put up a fight with Google on the operating systems front, but it would be a good strategy not to make the fight too loud or too public. Google is quickly becoming Microsoft's closest friend, in a perverse sort of way.

The U.S. government is already showing concerns about Google's search share and European Union regulators are starting to do the same. Microsoft is taking heat over the market share of its Internet Explorer product in Europe. Google is being aggressive using its search product to get people to download its competing Chrome browser. Microsoft has a chance to say that its browser share is eroding quickly, in part because of Google.

Microsoft has the opportunity to use the ascent of Google as a foil with regulators. It no longer has a dominant monopoly on PCs. Its operating system may have over 90 percent of the market, but Google is taking critical market penetration with search, which is being tethered to its own desktop apps.

Google may be the competition, but it is also an alternative target for antitrust authorities. If Microsoft wants to fight the search company, it should be discrete about it.

Douglas A. McIntyre is an editor at 24/7 Wall St.