By Aidan Malley

Published: 05:30 PM EST

Apple's upcoming release of Mac OS X Leopard could provide a major boost to the company's bottom line during the fall and could be bolstered even further by a new portable in January, according to a new report by analyst Gene Munster of investment firm Piper Jaffay.

The researcher maintained that Apple was "on track" to release Leopard by the end of October and that its timing could result in a surge of about $240 million to Apple's calendar fourth quarter results, even if adoption rates were similar to those from Mac OS X Tiger, which launched in April 2005. At the time, 15 percent of Apple's users bought either Tiger or a Mac preloaded with the software within six weeks of launch -- a feat possible due to the Mac maker's smaller customer base, but still widely believed to be a major accomplishment.

This uptake was expected to be higher as Apple's overall number of users running Mac OS X had nearly doubled from 12 to 23 million, Munster said. And unlike the launch of Windows Vista in January this year, Mac buyers were less likely to dent sales by waiting to receive the upgrade with a new computer, even as many enthusiasts upgraded or replaced existing systems specifically due to the new features.

"While we do not believe many consumers delay the purchase of a Mac because of Leopard, we expect its new features and updated look to be positive for Mac sales," the analyst wrote.

Munster supported the argument by drawing attention to projected Mac shipments in the quarter, which he predicted would range between 2.0 and 2.1 million units thanks in part to the new aluminum iMac and the back-to-school rush. iPhone and iPod sales traffic was likewise strong at retail outlets.

Apple was also unlikely to remain idle after the holiday season wrapped up, he added. The Piper Jaffray expert noted that the Cupertino, Calif.-based computer builder was most likely to expand its portable devices with at least one new system at Macworld show in January. Either a new Mac subnotebook or a multi-touch tablet was said to be '80 percent likely' for the IDG-run event.

Based on the new estimates, Piper Jaffray maintained its Outperform rating on Apple's stock, which surged 4 percent on Monday to close just short of $168.