As Microsoft launches Windows 7 and seeks to banish the ghost of its less-than-successful Vista OS, it is fighting to defend its primacy as the world's leading software company.

Apple and Google are leading markets that Microsoft once had hopes of extending its dominance to -- mobile telephony and Internet search. The Redmond, Washington, company also finds itself defending Office -- its biggest cash cow next to Windows -- from Google Apps and other Web-based productivity applications.

With billions of dollars of revenue still coming in, Microsoft remains the most successful software maker in the world. But the next year will be pivotal for Microsoft to prove it can hold the ground it already has and also gain a critical mass in search traffic and the emerging mobile ecosystem.

These stories form this news-analysis package:

Search: the market that created Microsoft's worst enemy

by Juan Carlos Perez

Has Microsoft just placed its last mobile bet?

by Nancy Gohring

MS Office battles Google in the cloud

by Elizabeth Montalbano

Microsoft seeks to leverage strengths in midmarket ERP

by Chris Kanaracus