As rumored, Jobs also announced a new Apple notebook computer, also based on the Core Duo, which will begin shipping in February.

Apple stunned the computer world last June when, after weeks of speculation, the company confirmed that it would end its long-standing relationship with IBM Corp. and transition from the PowerPC processor to Intel x86-based processors. The two companies had said they expected the transition to be complete by June of this year.

Delivering the keynote address at Macworld, both Jobs and Intel President and CEO Paul Otellini — who made a surprise appearance clad in a bunny suit and holding a silicon wafer — praised the hard work done by Apple and Intel engineers that enabled Apple to deliver Core Duo iMacs ahead of schedule.

"It's been incredible how well this has gone," Jobs said.

Otellini added that more than 1,000 Intel personnel worked on the project.

Jobs said the new iMac is as much as three times faster than its immediate predecessor, the iMac G5, in key specification areas. Other aspects of the new iMac, including the price, design, sizes and features remain the same, he said.

As had been rumored by analysts and Apple Web sites, Jobs also unveiled the MacBook Pro, a new line of notebooks based on the Core Duo, the dual-core Intel processor that had gone under the codename Yonah.

Jobs said the new notebook offers a four-fold increase in "performance-per-watt" and performance speeds of up to five times better than the PowerBook G4, Apple's most recent notebook.

Jobs said Apple has been working to ensure that its software will be "universal," running on both Core Duo and PowerPC Macs. Many of Apple's consumer applications already run on both, he said, and the company's professional applications will be universal by March.

However, most software developed by third parties is not yet universal. Jobs said a technology known as Rosetta is incorporated into Core Duo iMacs to allow them to run legacy applications until development is completed by third parties.