IBM has increased support for Linux with the introduction of versions of its Lotus Notes collaboration suite and Symphony productivity tools built to run on the open source OS -- and it's hoping the effort will help unseat Microsoft as the king of desktop software.

The company this week said it plans to ship what it calls its "Open Collaboration Client," made up of Lotus Notes 8 and Symphony, for Canonical's popular Ubuntu Linux distribution.

Lotus Notes 8 includes e-mail, calendaring, and contact management modules, while Symphony -- available as a free download -- features word processing, spreadsheet, and presentation applications build on the open source OpenOffice.org standard.

IBM also said this week that it's working with Red Hat to develop a version of the Open Collaboration Client for small and midsize businesses, which are increasingly a focus for IBM.

Under the plan, Red Hat will offer to its customers a version of the Red Hat Enterprise Linux Advanced Platform packaged with Lotus Notes, Symphony, and IBM's Domino messaging server.

Red Hat also will offer technical services to help resellers implement the package for customers.

IBM last year said it would offer versions of Lotus Notes and Symphony for Novell's SUSE Enterprise Linux distribution.

By porting key software to Linux, IBM is looking to give businesses one less reason to buy products from rival Microsoft -- which IBM said offers "a proprietary desktop model."

IBM's Linux efforts will "further address customer demands around choice," said Inna Kuznetsova, an IBM executive with responsibility for Linux, in a statement.