As Microsoft preps another version of its Office productivity suite, a small group of software vendors waits for an opening in the competitive landscape. However, analysts suggest that the greatest competition to Microsoft’s updated software remains older versions of Office.

According to sources, Microsoft Corp. is briefing selected partners and customers about the forthcoming family of Office desktop and server products. Office 12, the next version of the suite that will break the previous year-centric naming scheme, is due to arrive on shelves in summer 2006.

But in today’s market, the primary alternatives to Microsoft Office 2003 are Corel Corp.‘s WordPerfect Office 12, along with OpenOffice.org‘s OpenOffice and Sun Microsystems Inc.’s StarOffice, both of which share the same code base.

“WordPerfect Office still has a very loyal following in medium-sized enterprise and government,” said Michael Silver, vice president at Gartner Inc., of Stamford, Conn.

According to Corel, WordPerfect Office sports an installed base of some 20 million users, many found in the legal professions. The company recently offered a Legal Quick Start bundle, a package comprising WordPerfect Office 12, a set of legal templates and Gavel & Gown Software Inc.’s Amicus Attorney law practice management software.

Click here to read more about WordPerfect Office 12.

Recently celebrating its fourth birthday, the open-source OpenOffice also seeks a place in the market as a productivity solution and platform. Advocates often consider the Linux package as going hand-in-hand with Mozilla’s browser and e-mail client. A number of governmental agencies and businesses have switched from Office and adopted the package, especially in Europe.

How does Microsoft’s Office 2003 stack up against OpenOffice.org? Click here for comprehensive reviews of each suite.

Meanwhile, eWEEK Labs found many positive features in Sun’s StarOffice 7 productivity suite, calling it a “capable cross-platform alternative to Microsoft Office that comes at a price too attractive for enterprises to ignore.” While the user interface is different in many ways, the software “exhibited strong support” for Office’s file formats, the reviewers said.

Read more here of the StarOffice 7 review.

While calling StarOffice and OpenOffice “viable products,” analyst Silver said support, training and compatibility issues will constrain their widespread adoption. He said adoption is currently found in isolated departments or divisions of large enterprises, such as call centers, where the flow of documents is relatively confined.

Next Page: The luxury of a single software stack.