Well, Bing is a horrible search engine... it can't even index and find stuff on microsoft.com, the site of its owner!
Try it yourself... go to a page on their support site, say, support.microsoft.com/kb/2509997
swipe across the title of the page to select the first 7 words, in this case
"Unable to install updates in Windows Vista"
(so you can see it's a rather old page, not something they haven't had TIME to crawl and index)... copy and paste that phrase into the search bar (provided by Bing) at the top of the page there.
That support.microsoft.com page won't show up at all on the first page of bing results.
Now go to google.com and paste that same string into the search bar and click the button. Guess what site turns up as the top result?