BOSTON (Reuters) -- Amazon.com has started taking early orders for Microsoft's long-delayed Windows Vista operating system, offering versions of the product from $100 to $399.

The retailer's Web site said the software will be available on Jan. 30, and an Amazon (Charts) spokesman said on Tuesday the date was an estimate based on informal conversations with Microsoft and others in the computer industry.

Microsoft spokesman Lou Gellos declined to comment on Amazon's pre-sale, saying the software maker is still finalizing its pricing model. It has not set a release date for the new version of Windows, which sits on more than 90 percent of the world's personal computers.

Microsoft has repeatedly postponed the release of Windows Vista, which is already five years in the making. Quality assurance delays have put off the consumer version of Vista until early 2007 - after the crucial holiday shopping season. Vista is due to ship to corporate customers in November.

Goldman Sachs analyst Rick Sherlund said in a note to clients that Amazon's pricing on high-end versions of the software was above his forecasts.

Vista will be sold in more versions than Microsoft's current Windows XP operating system, with different lines targeted at consumers and businesses.

Amazon's pricing ranges from $100 for a basic upgrade version of Windows to $399 for a full "ultimate" version of the operating system, according to the retailer's Web site.

"The pricing of higher-end versions, which we believe will be more popular than the lower-end versions, may be more significant and longer lasting than the incremental upgrade revenues that have been of greatest focus by analysts," Sherlund said in his note.

Sherlund also said that a Jan. 30 release date would be about two months ahead of what he was expecting.

Microsoft (Charts) shares fell 0.4 percent on Nasdaq.

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