Support for Mac OS X and improved document format support are some of the improvements in Sun Microsystems' StarOffice 9, which was released on Monday.

It was a natural step for the Office suite to support Mac OS X, because of its increased popularity and because Apple users shouldn't be excluded from the move to open document formats, said Kent Åberg, business development manager for education and research at Sun Northern and Central Europe.

The support for many document formats is one of the main reasons customers should pick StarOffice, according to Sun. In addition to its native Open Document Format, it has support for Microsoft Office -- both legacy and new OOXML files -- and for PDF (Portable Document Format), so that such documents can be imported and edited.

Being able to open and edit more document formats without having to buy a number of different programs is becoming more important, according to Åberg.

"Otherwise, you can't get to your own information without buying the same software as the person who created the document," Aberg said.

Another important part of StarOffice 9 is improved support for extensions, which adds features including the ability to edit PDF files, create reports, blog and publish wikis.

Other changes in StarOffice 9 include a new start center, which gathers all the different tools in a way that's easy for the user to understand, and the addition of Mozilla's Thunderbird e-mail client and Lightning extension for calendaring.

Toppling Microsoft Office has so far proved very difficult for Sun, but Åberg is still hopeful.

"The interest in software based on open source is greater than ever, and more organizations, companies and people are starting to look at products which challenge established truths," he said.

But there are still those who hesitate to go with open-source software because they think that full support isn't available, according to Åberg.

StarOffice had less than 1 percent of the global market last year, and its free twin OpenOffice.org also had a relatively small installed base of approximately 5 percent, according to Gartner.

OpenOffice.org also had a 5 percent market share among U.S. Internet users over age 18, according to a survey done between May and November of this year by market researcher ClickStream Technologies.

Google Docs had a 1 percent market share in the same study.

StarOffice 9 and StarSuite 9, which is the Asian language counterpart, are available for US$34.95, compared to $69.95 for the previous version of the office suite.

Volume pricing for the enterprise starts at $25 per user. Enterprises can also choose to subscribe to a package that includes licensing and support, and comes in one- and three-year terms.