Facebook is in negotiations with Microsoft about acquiring advertising technology that could allow the social network displays ads on other websites. Facebook is in "serious" discussions with Microsoft about a deal to purchase Atlas Solutions, an ad-serving product that Microsoft acquired through its $6 billion acquisition of aQuantive in 2007, according to reports in the technology blogs Business Insider and AllThingsDigital on Thursday.The deal could allow Facebook to significantly expand its advertising business by showing ads on third-party websites, mounting a challenge to Google Inc's DoubleClick ad network.