Microsoft’s Vista has been a success so far, with more than 20 million copies shipped in its first month.  This is great news for Microsoft, but not for its competitors Google and Yahoo. Vista, launched in early 2007, faced some challenges like user complaints of recurring bugs and the release of Google Apps, a business software. But its numbers speak for themselves, and Vista’s success has exceeded Microsoft’s expectations.Vista’s predecessor, XP, did not sell nearly as many copies when it was first released.“We are encouraged to see such a positive consumer response to Windows Vista right out of the gate,” said Microsoft’s Bill Veghte.Vista aims to provide better search functions and is said to promote internet advertising. The software also boasts security enhancements and more user-minded features.The system offers six versions Home Basic, Home Premium, Business, Enterprise and Ultimate, plus a Starter Edition.“Since the launch of Windows Vista, Dell consumer customers have overwhelmingly chosen premium versions of the operating system that enable them to have a richer experience with music, video, photography and other computing applications they choose,” said Neil Hand, vice president of Dell’s Consumer Product Group.