Speaking to Wall Street analysts this morning, Microsoft CEO Steve Ballmer said the difficult economy continues to hurt the company's business, but he defended its spending by citing the opportunity to build market share and the need to compete effectively with strong rivals. In the area of PC operating systems, one competitor that he cited might come as a surprise: Google.

Ballmer made the comment in the context of Android, the Linux-based operating system that Google is using to lead its charge into the mobile-phone market. Via webcast, here's what he said.

"We’re very focused in on both Apple as a competitor and Linux as a competitor. I think the dynamic with Linux is changing somewhat. I assume we’re going to see Android-based, Linux-based laptops in addition to phones. We’ll see Google more as a competitor in the desktop operating system than we ever have before. The seams between what’s a phone operating system and a PC operating system will change and so we have ramped the investment in the client operating system."

Ballmer gave a broad update on Microsoft's business, acknowledging that Microsoft has lost market share in Web browsers but saying that the company sees Internet Explorer 8 as a chance to regain traction. He reiterated that Microsoft would like to do a search deal with Yahoo, but not a full acquisition.

He said he sees continued growth in the smart-phone market as an opportunity for Windows Mobile to gain market share, but he said the company does not plan to make its own phone. Discussing the company's new retail strategy, he said Microsoft's upcoming stores will carry hardware that runs its software, but he declined to go into detail, noting that planning for the stores is still under way.

Microsoft shares are down slightly, trading just over $17, following Ballmer's remarks.