Google Inc. will begin selling corporate America an online suite of software that includes e-mail, word processing, spreadsheets and calendar management, escalating the Internet search leader's invasion on technological turf traditionally dominated by Microsoft and IBM. The expansion, scheduled to be unveiled Thursday, threatens to bog down Microsoft Corp.'s efforts to persuade businesses to buy the latest version of its market-leading Office suite that was developed along with its new Vista operating system. Google's software bundle, to be sold for a $50 annual fee per user, also poses a challenge to International Business Machines Corp. and its Lotus suite. While Google's latest foray into the corporate software market seems unlikely to topple the status quo right away, AMR Research analyst Jim Murphy said it's only a matter of time before the Mountain View-based company becomes a major player. "This is just the beginning," Murphy said. "The real impact of what Google is trying to do probably won't be evident for another five years."