Microsoft has officially launched its Web-based email and Office services, part of its ongoing effort to keep Google at bay when it comes to business software.

"Office 365" has been available in a test version since last year. It combines Web-based versions of Word, Excel and other Office applications. It also includes the Exchange e-mail system, SharePoint online collaboration technology and Microsoft's instant messaging, Internet phone and video conferencing system.

Google Inc. has its own set of office software that's based in the "cloud," that is, hosted on remote servers and accessed online instead of on users' desktop computers.

Microsoft Corp. said Tuesday that it plans to charge $2 to $27 per month for Office 365 depending on what's included. Google Apps costs $4 or $5 per month.