"We got the prices straight off Microsoft's price lists," said Sean Sundwall, a spokesman for Amazon.
Microsoft did not immediately respond to a request for comment or clarification on the prices and delivery date posted by Amazon.
For their part, some industry watchers saw the Amazon-reported pricing as comparable to existing costs for Windows XP, while others noted that, at least in some instances, Microsoft is raising prices. One analyst thought both arguments had merit.
"The pricing is a difficult one to do comparisons with the past," said Joe Wilcox, analyst with JupiterResearch. "It depends a lot on how you want to look at it."
On one hand, Wilcox saw Microsoft positioning Home Basic as "pretty basic" in functionality, yet is charging the same as Windows XP Home. "You could argue that it's a price increase across the board." On the other hand, Microsoft's added new versions and shifted some functionality -- notably the Windows Media Center set, which hasn't been available at retail -- to those editions. "So you could say it's in line with prices today."