I've now read one dozen reports about Microsoft buying Greenfield Online, which owns a Web research business based in my home state of Connecticut as well as European comparison shopping site Ciao.

My favorite analysis was published Friday by my colleague Joe Wilcox for Microsoft Watch because he correctly outlines how Microsoft made the $486 million buy for search market share.

Specifically, Joe notes how Microsoft will use Ciao to aggressively push Windows Live Cashback into the European market. Cashback, which Microsoft molded from its Jellyfish comparison purchase last October, gives back a percentage of the purchase price to the buyers.

Microsoft said Ciao will serve as the foundation for its Live Search efforts abroad. The company is positioning it as a promising offensive move and neither Joe nor other analysts challenge that position. I challenge that position.

Given Google's mountainous lead in search, which comScore says is around 62 percent in the United States and a whopping 75 percent in the United Kingdom, I can only conclude Microsoft's move is defensive.

Microsoft's share, as Joe noted from comScore, is around 3.4 percent in the United Kingdom and 9 percent in the United States. These figures are so small and so insubstantial as to be negligible.

To my mind, Microsoft paid almost half a billion dollars for Ciao to keep Google from getting it. I've written a few pieces in which I discuss how e-commerce is the one area Google really hasn't leveraged.

Microsoft surely realizes it and now has acquired leading sites such as Jellyfish and Ciao within the space of a year.

Think of the gold mine of information about consumers that can be mined from comparison shopping sites. That's plenty of info a search provider such as Google can mine to help target more users for search ads.

Right now, there are enough e-commerce sites to parallel the properties of the Monopoly board game a few times over. In Jellyfish, Microsoft plucked an Atlantic Avenue. With Ciao, Microsoft has acquired Marvin Gardens. 

The sad thing is, while this might seem like a clever strategy, all Microsoft's acquiring will do is keep Google from owning 75, 80 or 85 percent of the search market. Indeed, Live Search Cashback is just not getting it done for Microsoft in the early going.

Don't believe me? Check out Erik Schonfeld's piece on TechCrunch last week, where he writes:

After Live Cashback launched in May, Microsoft saw an initial one-month boost in its share of the U.S. search market (from 8.5 percent in May to 9.2 percent in June). But in July, its share slipped again down to 8.9 percent, according to comScore. Although we only have two months of full data (June and July) since launch to evaluate, it doesn't look like Cashback is having any effect.

With buys like Jellyfish and Ciao, Microsoft may appear like they are on the offensive, but the results just don't add up.

I can only conclude that Microsoft believes its best offensive versus Google at this point is to play defense as in, keep these e-commerce properties from Google's own Monopoly set.

Aggressive defense can come back to haunt you. A seven-man blitz on a short toss to the flat will get you burned.

How many more e-commerce properties is Google going to let Microsoft buy? Will Google wait until Microsoft captures a Priceline, or an Expedia?

Indeed, Microsoft's moves may just inspire Google to buy its own Park Place or Boardwalk in the great Monopoly game of search.