I would've thought this was obvious. Google didn't just pay $300 to stop Firefox from using Bing, although I'm sure that played a big role, too, but I believe the reason Mozilla got $300 million was because they knew how to negotiate the price up. I don't think Mozilla really wanted to change to Bing.<p>Also, Google is a lot better off having an ally in Mozilla. Not so much because they don't want Bing to get a lot of users, but because together with Mozilla they have over 50% of the browser market share, and since the whole total of that market share includes very modern browser versions(Chrome always on latest version, Firefox not too far behind with the old ones), Google and Mozilla can pretty much dictate where the web is going now. I wouldn't be surprised if for those $300 million they also got Mozilla to accept using Native Client in Firefox later on. I think this part of the partnership matters more than just stopping Bing from becoming the default search on Firefox.