Microsoft on Monday replaced Yahoo's search technology with its own homespun software and will kick off a huge advertising campaign to supplant Google in consumers' hearts. As expected, MSN, a unit of the software giant, has taken its Web search technology out of the laboratory, and placed it on MSN's newly redesigned home page in 25 countries. Two and a half years in the making, MSN Search will now be the focal point of the updated, lighter-weight site; and it is the subject of Microsoft's newest ad campaign, which includes television, print, Internet and outdoor promotions. MSN Search Vice President...