Apple's shares have dipped below the hard-won $30 mark as investors digest the news that no iMacs will be on sale in the crucial US educational buying season.

Many investment houses regard this as a blip, and continue to recommend Apple's stock as a Buy, describing the lack of iMac as a stock-buying opportunity.

However, this morning's Business Week points out that Apple's hardware sales account for 58 per cent of its revenues, including iMacs, eMacs, Power Macs, PowerBooks and iBooks.

"By focusing so hard on the iPod and the iTunes Music Store, has CEO Steve Jobs taken his eye off the Macintosh franchise?" Business Week asks.

The actual financial impact of missed iMac sales may not be so stark, particularly for a company that is shifting its focus away from computer hardware and toward award-winning consumer gadgets and market-leading software tools.

However, changes in accountancy rules – such as the need to expense stock options – will impact negatively on the company's bottom-line, analysts warn. They expect Apple to report $235 million in net earnings in its current financial year, but that expensing of stock options could reduce its net to just over $100 million.

"That's why reinvigorating the iMac is urgent," the report adds, adding that this is particularly true of the US education market, where Apple now has 14.1 per cent of the market.

Apple also makes more money per unit on its Macs than its competitors, the report adds. "Two years ago, says First Albany Capital analyst Joel Wagonfeld, "the average selling price of a Mac was $154 higher than that of a Windows PC. Now it's about $400 higher."

However, optimism also surrounds the new iMac: "If the new iMac is a hit, Jobs's focus on innovation will again be vindicated", the report concludes.