Pilot campaigns using MSN's adCenter paid-search system are generating high conversion rates but Microsoft should more quickly expand the program, search marketers say, according to DM News. Apparently, demand is high but MSN is limiting the testing as it continues to serve Yahoo search ads. In the U.S., some 800 advertisers and agencies have been involved in the most recent phase of testing. MSN plans to release the test results in the first quarter and launch adCenter sometime in the first half of 2006.

"The ROI is very good because prices are so low," said Danielle Leitch, VP of marketing and analytics at More Visibility. "Some of the advertisers are the only ones on the keywords." Despite the high ROI, Google and Yahoo have much greater traffic volume, so MSN's overall effectiveness is difficult to measure.

adCenter's behavioral and demographic targeting features, however, are its differentiators, and they are apparently helping some advertisers, who are able to boost their bids in certain demographics.

But those behavioral and demographic features can overwhelm some advertisers, and others simply would not need to use them because their products appeal to a broad range of consumers.