IBM has introduced a line of business computers that eschew Microsoft's ubiquitous desktop environment in favor of an amalgam of open source software.

The system, which IBM calls the Open Collaboration Client, combines the Linux operating system with IBM's open source Lotus Symphony desktop package.

Symphony includes word processing, presentation, and spreadsheet applications based on the Open Document Format. IBM Lotus Notes apps are also available.

The system is designed to run in a virtual configuration, with the software stored both locally and on remote servers. IBM teamed up with Canonical and Virtual Bridges to create the offering. "Today's news builds on announcements through 2008 around delivering Microsoft alternatives in conjunction with our partners," IBM said in a statement Thursday.

IBM claims the system can save businesses $500 to $800 per user on Microsoft software licenses and an additional $258 per user "since there is no need to upgrade hardware to support Windows Vista and Office."

Big Blue also claims the system's virtual setup affords savings of $60 to $118 per user on power and air conditioning costs, and that it will also help companies reduce IT support expenses. "For this virtual system, all administrative intervention is done on consolidated virtual machines in the data center through deployment of standard images," IBM said.

IBM's push into non-Windows computing is the latest challenge for Microsoft's core operating system franchise. Apple, with its business-friendly Mac OS X system, is starting to make inroads into corporate computing. And so-called netbooks -- low-cost systems that are not capable of running Vista -- are gaining popularity in emerging markets and other high-growth niches.

Revenue from Microsoft's Client division, which derives mostly from Vista now that Windows XP has been formally retired, edged up just 2%, year over year, to $4.21 billion in Microsoft's fiscal first quarter, despite the fact that the overall PC market grew 10% to 12% during the same period.

IBM is offering virtual systems based on the Open Collaboration Client through its Global Services outsourcing and system integration unit.