Microsoft ( MSFT) is terrified of Google's ( GOOG) plans to buy DoubleClick. As well it should be. Last week, the Redmond, Wash., software giant's push to block Google's proposed acquisition of ad-serving firm DoubleClick reached a fevered pitch. Microsoft's lawyers told a Senate subcommittee investigating the deal that a combined entity would violate antitrust laws and would make it that much harder for anyone to take on Google in the online ad space. Unfortunately, for Microsoft -- and fortunately, for Google investors enjoying another 52-week high -- the software giant is probably only half right. Despite Microsoft's flurry to block the deal, a Google/DoubleClick combination isn't likely to be found to violate antitrust laws. But much as Microsoft has been dreading, "GoogleClick" would occupy a prime position to further capitalize on the booming online ad market in which Microsoft has long been struggling. While last week's courtroom theatrics made headlines, Microsoft has been working frantically behind the scenes to scuttle the Google and DoubleClick deal. Microsoft has hired a Washington lobbying firm and a public relations firm, and CEO Steve Ballmer and other top executives have placed phone calls to rally support, according to the blog SiliconAlleyInsider. And along with AT&T ( T), Microsoft has funded a research paper written by the AEI-Brookings Joint Center for Regulatory Studies that agrees with its legal position against the deal.