Redmond (WA) - A rare Microsoft apology was issued this week, in response to complaints that Windows Vista Ultimate wasn’t living up to update expectations outlined by the software giant.

One of the selling points of Microsoft’s elite operating system is a slate of exclusive "extras", which Microsoft promised to expand in the months following its debut.

To date, only four Ultimate extras are available - Windows BitLocker Drive Preparation, Secure Online Key Backup, an exclusive Texas Hold ’Em game, and 16 language packs for Windows multi-language user interface. Each of these was release on or near Vista’s launch during the last winter season.

At its launch event, Microsoft showed off one other main bonus feature, Windows Dreamscene. This extra will let users set up a video to run as their desktop background. 20 other language packs were also supposed to be released in a more timely manner.

"We apologize for taking so long to provide a status update to customers," said Vista Ultimate director Barry Goffe in an official statement. He predicts the delayed extras should be available by the end of summer, saying time is still needed to fine tune these extras so they "meet the high quality bar required by our enthusiastic customers."

Microsoft has previously said additional extras will be released on a continuous basis. Goffe did not mention anything about other upcoming extras.