Updated from 8:50 a.m. EST

Microsoft ( MSFT) will delay the consumer version of Vista, the next version of Windows, until January 2007, the company announced Tuesday.

But a version for business will be released in November of this year.

The news ruffled investors who have been assuming that Vista, which is seen as the company's most important product release in years, will ship on time and be a catalyst for strong sales growth. In premarket trading on Instinet Wednesday, Microsoft shares were down 65 cents, or 2.3%, to $27.09.

Computer hardware stocks also took a hit. Intel ( INTC) fell 6 cents to $19.72, while Dell ( DELL) lost 35 cents to $29.92. Apple ( AAPL) rose 74 cents to $62.55.

Analysts said the hit to personal computers and related segments could be meaningful, although some, like Lehman Brothers, had already taken down their forecasts because of weakness that preceded Microsoft's news.

"We are not, at this time, changing our PC forecast as we had already cut our 2006 projections by approximately 5 million units earlier this week due to weaker than expected notebook seasonality and concerns over the potential impact from Vista," Lehman said. "Assuming a 10%-20% deferral of purchases by consumers (roughly 40% of the market), the EPS impact to Dell would be approximately half a cent to 2 cents a share, and approximately half a cent to 1.5 cents to Hewlett-Packard in the fourth quarter of 2006."

To view Jim Cramer's video take on Microsoft's disappointment and what it might mean for the market, click here .

Jim Allchin, Microsoft's Windows czar, said businesses that buy Windows via licenses will be able to get Vista in November. New PCs for consumers will be loaded with Vista as of January, he said on a call with analysts and reporters.

Allchin said the delay in the consumer version was necessary because Microsoft couldn't guarantee that Vista would be ready soon enough before the holiday season to accommodate some PC makers. "Our industry partners were telling us that for the December selling period, they need quite a bit of time and a high level of certainty about the date of availability ."

Although the delay is just a few weeks, the timing couldn't be much worse since it will obviously impact holiday sales of PCs, games and software. The news is particularly painful since analysts now believe that sales of both desktop and notebook PCs this year will be slower than they had initially thought.