So much for peace on earth. Microsoft has launched a holiday season offensive against Google, claiming that search results on its rival's shopping site are bought and paid for.

"Google’s new redesigned shopping vertical now decides what to show you -- and how prominently to display what product offers they show -- based partially on how much a merchant selling the product has paid Google," Microsoft said.

This refers to new rules that Google adopted for its shopping site. Google Shopping now charges merchants who participate in its Product Listing Ads program fees on a per-click or cost-per-acquisition basis. The enhanced results include product images, prices and merchant information.

[ What isn't Microsoft saying about Windows 8 sales? See Microsoft's Windows 8 Numbers Meaningless. ]

Google makes no bones about the program. "This new product discovery experience will be called Google Shopping and the transition will be complete this fall," the search giant stated in a recent blog post. "We believe that having a commercial relationship with merchants will encourage them to keep their product information fresh and up to date."

"Higher quality data—whether it’s accurate prices, the latest offers or product availability—should mean better shopping results for users, which in turn should create higher quality traffic for merchants," Google's post said.

Microsoft begs to differ. Google's pay-to-play program means the results that potential shoppers get will be based more on what merchants are willing to pony up than on query relevancy, Microsoft said.

"Merchants can literally pay to improve their chances to display their product offers higher than others inside of Google’s shopping 'search,' even if it’s not necessarily better or cheaper," Microsoft said. "That’s not right, it’s not transparent, it’s not what you expect from search, and it’s not how we at Bing think search engines should help consumers get the best prices and selection when shopping."

Microsoft said it maintains a hard line between Bing ads and Bing search results. "We won’t let who pays us for ads or other services affect what you see in your shopping search results. Search results are one thing; ads are another."

Microsoft has launched a marketing campaign that warns online shoppers searching for the best bargains on Google that they might be getting "Scroogled."

"We won’t switch to pay-to-rank to allow fees to influence the ranking of shopping search results. In short, we think that too many shoppers who use Google for their shopping are getting "Scroogled" when they should be getting fair, honest, open search results," the company said.

Microsoft is looking to put a dent in Google's stranglehold on the search market. Google held 66.9% of the U.S. search market as of October, according to the latest data from Comscore, compared to just 16% for Microsoft.

Upgrading isn't the easy decision that Win 7 was. We take a close look at Server 2012, changes to mobility and security, and more in the new Here Comes Windows 8 issue of InformationWeek. Also in this issue: Why you should have the difficult conversations about the value of OS and PC upgrades before discussing Windows 8. (Free registration required.)