It's on! Google has announced on its own corporate blog its intention to compete with Microsoft in the PC operating system market. That's right: It's Mountain View versus Redmond, the upstart search engine/advertising company against the world's No. 1 software company. Google has now stated its intention to expand its Chrome OS for netbooks into the desktop PC realm--of which MSFT presently controls, um, about 99.9 percent of the market. (Or 99.999 of the corporate market.) First Google invaded our search engines. Then it annexed the smartphone sector with Android. But this is different, like Germany turning against Russia during World War II. (We'll leave it to you to assign which party is analogous to which nation.) Or: Marc Andreessen and Sergey Brin in a steel-cage death match against Bill Gates and Steve Ballmer. As Google would have it, this is nothing less than the future at war with the past. As Andreessen told The New York Times, the Web-based "Chrome is basically a modern operating system," unlike Windows 7, which comes on old-fashioned silver discs. Ballmer? We believe the ball is now in your court. Please swing away.