Another user, Steven Naylor, vice president and director of IT at Federal Home Loan Bank of Topeka in Kansas, said he intends to stick to existing plans and hold off on any upgrade to Vista until after Microsoft's first service pack is released.

"For most companies, this slip will not be an issue, because it will take them 18 months for testing and planning before they can start deploying Windows Vista," said Michael Silver, an analyst at Gartner Inc.

"Microsoft could ship the business editions into 2007 without a big impact on what most companies would do, and that's certainly possible," according to Silver.

In no big rush

Both Gartner and Forrester Research Inc. predicted last year that enterprise adoption of Vista would be sluggish. For instance, Forrester said in December that its surveys indicated that only a third of big business users planned to start deploying Vista when it became available -- or even by the time the Service Pack 1 update ships, which typically takes a year or so.