As if Yahoo! wasn’t already kicking itself for not taking Microsoft’s $31/share offer, they must be doubled over with pain now on the latest search engine data.

Just one day after formally launching – Microsoft’s new search engine called Bing has overtaken Yahoo to rank second among the most used online search engines in America.

According to the Web analytics firm StatCounter, Bing grabbed 16.28 percent of all searches in the country, doubling the share Microsoft Live Search had just a week earlier.

Yahoo, meanwhile, has dropped from 18 percent to 10.22 percent. Forrester Research analyst Shar VanBoskirk told PC World that because both Bing and Yahoo combine content and search, it's only natural that Yahoo would be hit by the new competition first.