Microsoft this week formally launched a free, online version of its popular Office desktop productivity suite.

Microsoft Office 2010 In Pictures

Office Web, as it's called, includes online editions of Word, Excel, and PowerPoint. The Web apps are formally part of Microsoft Office 2010, which rolls out to consumers next week. Users in the U.S, UK, Canada and Ireland can immediately access Office Web applications through Microsoft's Windows Live SkyDrive portal.

Microsoft plans to introduce Office Web in other countries in the coming weeks, the company said.

Making a version of Office available online allows Microsoft to protect its flank from Web-based software from Google and from free, open source-based offerings, such as IBM's Lotus Symphony product.

Some early reviews , however, indicate Office Web is less robust than Google Docs.

Office Web Apps are tailored specifically for the online environment. For instance, the Office Web version of PowerPoint will not contain the desktop version's high-performance video editing tools. The Web apps, on the other hand, will offer features that won't be found on the desktop versions, such as the ability to embed tags into documents and post them on blogs.

Businesses that purchase volume subscriptions to Office will receive access to the Office Web Apps at no additional charge. Microsoft has about 90 million such customers. It also has roughly 400 million Windows Live users, adding up to a potential installed base of almost a half billion users for Office Web.

The boxed version of Office 2010 is available June 15. The Professional edition is priced at $499, while the download is $349. There's also significant price discrepancies between boxed and download delivery for other versions as well.

For the Home & Student version, it's $149 vs $119. For Home & Business, it's $279 vs $199.