By Katie Marsal

Published: 10:40 AM EST

A pair of new iMacs expected to be released by Apple Inc. on Tuesday should shift investor focus away from the early stages of iPhone sales and back onto the more significant story of the Mac market share growth, according to investment research firm Piper Jaffray.

"We believe Apple will introduce redesigned iMacs at a press event tomorrow," analyst Gene Munster wrote in a research note to clients on Monday morning. "Since early this summer when AppleInsider first issued the story, we have been anticipating an iMac update with a radically new form-factor."

Should the new iMacs arrive as anticipated, Munster believes they could drive upside to his September quarter Mac shipment estimate of 1.9 million systems. He told investors that Apple appears to be on a path of replicating its iPod strategy within its Mac business.

"For the past two years Apple has announced new iPod models in September, ahead of the holiday shopping season; this year Apple is announcing upgraded Macs ahead of the education buying season," the analyst wrote. "And similar to the successful holiday quarters in 2005 and 2006, we expect Mac sales in the 2007 education season to be strong."

Munster also told clients that believes the new iMacs will shift investor focus away from the early stages of iPhone sales and back onto the more significant story of Mac market share growth. He noted that during the last calendar quarter, Apple's worldwide Mac market share rose to a historical high of 3.0 percent, up from 2.6 percent in March and 2.5 percent in December.

In his note to clients, the Piper Jaffray analyst said he does not have any hard evidence of other products Apple may introduce at its event on Tuesday. However, some "unlikely" possibilities could include a new version of the company's iLife digital media suite, new monitors with built-in iSight cameras, or upgraded MacBooks.

"A 13-inch MacBook Pro model featuring an ultra-portable, lightweight enclosure is also a possibility," he wrote.

Munster maintains an Outperform rating and $211 price target on shares of the Cupertino-based Mac maker.