By Katie Marsal

Published: 05:15 PM EST

Sales during Mac OS X Leopard's first full month on store shelves reached an unprecedented high for any Apple operating system release to date, according to new research from the NPD Group.

When compared to OS sales in May 2005 -- the first complete month Mac OS X Tiger was available to customers -- Apple's November 2007 sales of Leopard were 20.5 percent higher, says NPD directing analyst Chris Swenson. This amount does not include copies pre-installed with new Macs but does blend both online and retail figures.

In comparison, Tiger represented a 30 percent increase over the 2003 Panther update, and 100 percent more than the 2002 release of Jaguar.

"It's really stunning to see Apple have one blow-out OS launch after another," Swenson tells AppleInsider. "It's clear that Apple has hit upon the right strategy for rolling out new versions of its OS."

Notably, the climb in dollar volume is disproportionately higher. Income from Leopard climbed by 32.8 percent. Family pack sales accounted for much of this, accounting for almost exactly one third of Leopard sales at 32.8 percent versus only 20.4 percent for the Tiger introduction and boosting the average sales price upwards as a result.

A lack of discounts from third-party stores for the OS helped account for the drop, according to the report.

Although Apple is said to have had inadvertently good timing by launching at the peak of the holiday shopping season and has been helped by a larger number of retail stores, the record has come in spite of the Cupertino, Calif.-based firm stepping down its promotional campaigns for the Leopard debut. A limited-run promotion, dubbed "Free Human With Purchase," helped buyers upgrade their Macs to Tiger with free in-store installation and an hour-long introduction to new features. Leopard's now standard Migration Assistant and the sheer cost of devoting staff to the project likely made it unnecessary, according to Swenson.

The Mac maker may also have determined that such programs are ineffective -- a lesson lost on CompUSA, the analyst observes. While the now in-liquidation retailer was one of Microsoft's most active retail partners for the Windows Vista launch in January and offered help for users upgrading to the new Microsoft package, few customers are believed to have been aware of the option or exercised it. Apple is reportedly under less pressure to do so given the constant presence of its Genius Bar, which provides both consultation and technical help.

"The Apple geniuses are [always] there for you," Swenson notes. "Apple didn't see the need to have 'dedicated free humans' just for the Leopard launch."