Microsoft, still trying to come from behind in the portable music market, is confirming plans to sell the upcoming Zune HD 16GB for $219.99 and the 32GB version for $289.99 -- noticeably less than Apple iPod models with the same storage capacity.

The numbers confirm recent leaks. The Redmond company early Thursday also announced that release date for the Zune HD will be Sept. 15. Preorders will start Thursday from Amazon.com, Best Buy, Walmart and Microsoft.

By comparison, Apple sells the 16GB iPod touch for $299 and the 32GB model for $399. Those devices have the advantage of sharing a large library of applications with the iPhone, adding to their value as miniature computing devices, connecting to the Internet via wifi.

Microsoft, for its part, continues to focus heavily on music with its Zune lineup, but the new versions add enhanced video capabilities and a streamlined web browser, for accessing the Internet over its built-in wifi connection. Other new features include an HD radio and an OLED screen. The slim device has so far received positive reviews from technology blogs and news sites.

The company launched the Zune in fall 2006, making the upcoming holiday the fourth for Microsoft's iPod challenger. Microsoft has yet to gain significant ground against Apple in the market for music devices, but Zune is increasingly becoming the central music brand for the company, expected to supply underlying software for elements of Xbox Live and Windows Mobile.

Coming Thursday on TechFlash: Video tour of the Zune HD