Jan.30 - Microsoft Corp. rolled out Windows Vista at retailers in 70 countries on Tuesday, delivering a new computer operating system that aims to better manage the explosion of digital media and protect users from the dangers of the Internet.Windows runs on more than 95 percent of the world's computers, and the long-delayed new version is the first major release of a new Microsoft operating system since it introduced Windows XP in 2001.In the first year of its release, Vista, which required a $6 billion investment from Microsoft, will be installed on more than 100 million PCs worldwide, according to research reports.