I think the difference in quality between Google and Bing search results is negligible; at this point it's just a matter of mindshare as to whether people, on average, go to www.google.com or to www.bing.com when they want to look something up. There's no vendor lock-in propping up Google, to the extent that there is behind the Windows or iTunes monopolies. Mindshare can be altered, Microsoft just needs to figure out how to do it.