In a note to clients issued Tuesday, Think Equities’ Rajesh Ghai largely avoids speculating about what Apple (AAPL) might announce at Wednesday’s special event.

Instead he concentrates on the iPad, raising his sales estimates and ticking off the reasons he believes Apple’s tablet could be, in his words, “the Trojan horse that finally gets Apple into the enterprise.” Among them:

• The tablet is here to stay. The form factor is a hit, he says, and rapidly becoming a standard issue personal hardware device for business types, alongside the notebook and desktop PC.
• Speed is of the essence. “For instance,” he writes, “we are told the product’s relatively short startup time relative to the notebook is a big plus for time-challenged business people.”
• It’s a global phenomenon. “While the rapid adoption by the U.S. consumer was evident last quarter,” he writes, “our contacts overseas suggest that the geographic expansion of the iPad has been equally successful overseas.”
• Supply has finally caught up to demand. “We believe it is positive and timely not only from the point of view of Apple’s ability to meet rapidly increasing demand but also because it prevents consumers from seeking out competitor products, such as the Samsung Galaxy tablet likely to be launched in early September.”
• Apple is in the catbird seat. “Considering the iPad’s early lead and traction in the tablet form factor,” he writes, “we believe it could be the product that finally makes Apple a broader IT hardware supplier into the enterprise.”
• Apple will sell iPads by the millions. “We note that the PC market is about 300-350M units annually,” he estimates. “If the tablet market becomes about 20% of its size in 2011, the tablet market can be seen more than tripling in size next year.”

Ghai now estimates that Apple will sell 5.75 million iPads in the quarter that ends Sept. 25, up from an earlier estimate of 5 million, and 22 million in fiscal 2011, up from 19.5 million.

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