The IDC quarterly forecast of worldwide x86 server OS shipments for the year 2009, released last month, has Linux declining year over year by 16.1 percent, from 1.747 million shipments last year to nearly 1.47 million in 2009. Windows Server is slated to drop by 12.8 percent, from 5.75 million units in 2008 to about 5.016 million units this year, the syndicated report stated.

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However, this news of Linux's greater slippage on a percentage basis is not much consolation for Microsoft, stressed analyst Matthew Eastwood, group vice president for enterprise platform research. "It's not exactly a great story for them, either," he said.

"We're projecting the market to decline for everybody," down double digits this year, Eastwood said.

The reason Linux might slip a bit more than Windows Server is that large datacenters running Linux have felt the effects of the market slowdown and are pulling back on installations, according to Eastwood. With Windows, many customers are on enterprise site licenses and deploying Windows does not cost any extra.