IBM (NYSE: IBM) will start offering PCs that do not run Microsoft (NASDAQ: MSFT) Windows operating system. According to The Wall Street Journal, "IBM says it has created a "Microsoft-free" virtual desktop -- a complete suite of applications that run on a backroom server and don't require Microsoft software or costly desktop hardware."

The new machines will use Linux and IBM software and will cost as little as $59 per machine, which could save companies several hundred dollars per desktop.

While IBM would say it is offering the new package because "server side" computing allows many workstations to run from one server, which saves money, there's no denying this is also an aggressive move against Redmond.

Windows is already under siege. The Apple (NASDAQ: AAPL) operating system continues to take market share as Mac sales increase. The latest version of Windows, Vista, is so unpopular that many companies have refused to upgrade to it. Open source Linux has not been very successful against Microsoft, but IBM could help change that.

For Microsoft, PC users slowly moving away from Windows to a number of other alternatives is death by a thousand cuts. There is no one thing that the software company can do to keep customers other than rush a more popular version of Windows to market. That would mean it is more likely to have annoying "bugs."

Windows is where Microsoft makes its money, for now at least.

Douglas A. McIntyre is an editor at 247wallst.com.