By Reuters: The launch of Apples latest operating system, Leopard, was its best ever, a research group said Monday.

When comparing the first full month of sales of Apple Mac OS 10.5 زLeopard (November 2007) to the first full month of sales for Mac OS 10.4 Tiger

(May 2005), dollar volume for Leopard was up 32.8 percent, and unit volume was up 20.5 percent, NPD Group said in a statement.

Apple, maker of the Macintosh computer, the iPod digital-music player and the iPhone smartphone, started selling Leopard in late October, after a four-month delay due to the companys work on the iPhone.

The new version of Appleصs OS X software costs $129 for a single user and $199 for a زfamily pack that can be installed on as many as five computers in a single household.