Thomas Cavanaugh, an IT analyst at a financial services firm that he declined to name, doesn't believe that in five years people will be convinced they should move from Unix systems to Windows. "They still remember NT, and I don't think even in five years they are going to forget that," he said, referring to a previous Windows operating system aimed at enterprise users.

Cavanaugh's company uses IBM's AIX and Solaris, proven technologies and operating systems that will be around for years. But "if there were new applications that were only coming out on Windows -- not coming out on AIX and Solaris -- that might drive the shift," he said.

Other forecasts include an estimate that the average IT budget will grow this year by 2.7 percent. Energy costs, currency fluctuations, the threats of bird flu and terrorism aren't holding IT spending back. "Despite these uncertainties, growth is still on the business agenda," said Sondergaard.

Enck said he expects Advanced Micro Devices Inc.'s Opteron processor to continue to expand its market share, which he said is good for users because it will ensure competition in the x86 market. But Enck also said he believes Itanium's major user base will be those running HP-UX system.

Enck said deployments of Unix will decline as independent software vendors become platform-agnostic, focusing on J2EE or service-orientated architectures such as .Net.