Interesting article
http://money.cnn.com/2012/07/02/technology/microsoft-aquantive/index.htm

Bing, Microsoft's search engine, currently maintains a 15.4% share of the search market, up from 8.4% when Bing launched, according to online data tracker comScore (SCOR). That's a nice jump, but Google still commands 66.7% of the market -- up 1.7 percentage points from the 65% it held when Bing debuted.
Most of the share that Bing has gained has actually come from third-place Yahoo (YHOO, Fortune 500). The rest has come from search cellar-dwellers Ask.com and AOL (AOL).
So Microsoft has just gutted Yahoo and not made inroads against Google. Strange really with the amount of people complaining about Googles results lately.

Still I must admit I almost never use yahoo or bing for anything...