Microsoft will officially launch Office 2010 to businesses at an event slated for 12 May, the company announced today.

The company did not immediately respond to questions about the timing of when enterprises with volume license deals will be able to obtain the finished product. Typically, those customers can download new Microsoft software weeks or even months before the same programs are available to consumers. When Microsoft rolled out Office 2007, for example, business customers had the suite more than two months before consumers.

Office 2010 is set to go on general sale sometime in June, but Microsoft has not yet disclosed an exact ship date.

As expected, Microsoft also unveiled a program that provides a free upgrade to Office 2010 for customers who purchase the older Office 2007 between now and Sept. 30.

Earlier this week, Microsoft's chief financial officer had confirmed that the Office 2010 Technology Guarantee Program would launch this month . Last month, details of the free Office 2010 upgrade program leaked to the Web when a Microsoft technology specialist briefly posted information to the firm's partner community site.

Customers who purchase an eligible copy of Office 2007 between 5 March and 30 September will be allowed to download a corresponding edition of Office 2010 for free when the new suite is available in June. Users who want a DVD installation disc will have to pay a small shipping-and-handling fee. Microsoft said fees would be announced in June.

Buyers of Office Home and Student 2007 will receive a free copy of Office Home and Student 2010, while buyers of Office Standard 2007 and Office Basic 2007 will be eligible for a free copy of Office Home and Business 2010, a new addition to the Office lineup. Purchases of Office Small Business 2007, Office Professional 2007 or Office Ultimate 2007 will be eligible for a free copy of Office Professional 2010.

Office 2010 is the first of Microsoft's suite line to drop less-expensive upgrade editions. Instead, Microsoft plans to sell single-licence activation keys via its online store and select retail outlets to customers who want to upgrade from older editions, or from the bare bones Office Starter 2010 that will come pre-installed on new PCs.

There is a limit of 25 free upgrades per person, a standard Microsoft practice meant to push businesses with multiple copies to its volume licensing deals.

Microsoft has set up a site that spells out the upgrade programme in detail.