Under the program, small businesses that purchase paid search ads through Microsoft's Office Live service will see their search listings appear on Web sites operated by Ask.com and its partners, in addition to Microsoft's Windows Live and MSN.com sites.

Microsoft's Office Live customers have access to adManager -- a Microsoft tool that allows users to select and bid on key words to be used in paid search campaigns. Under the alliance with Ask.com, adManager will now automatically extend the campaigns beyond Microsoft sites to Ask.com sites through integration with Ask.com's Ask Sponsored Listings service, Microsoft said.

The deal could make Microsoft a more attractive service provider for businesses contemplating a paid search campaign. The company's Web sites captured about 13% of all search traffic in June, according to market watcher Comscore. The addition of Ask.com's sites to its paid search service will expose Microsoft's customer listings to an additional 5% of search traffic.

That takes Microsoft's network a step closer to Yahoo, which in June captured 25.1% of all search traffic, and Google, which grabbed 49.5% of traffic for the month, according to Comscore.

With its software business under pressure from providers of open source and Web-based applications, Microsoft is looking for ways to boost its revenue from online advertising. In its most recent third quarter, the company said sales of online services—which includes paid search listings—increased 11% to $623 million.

Given its importance to the company's future, analysts will be watching that number closely when Microsoft reports fourth quarter earnings on Thursday.