Speaking to over 5,000 Apple devotees attending the Macworld Expo here, Apple chief executive officer Steve Jobs kicked off the the show by unveiled his vision of Apple's systems as the hub of the evolving "digital lifestyle."

Referring to its most recent quarter, when Apple's revenue fell $600 million short of expectation, Jobs stood firm against prevailing industry speculation on the death of the personal computer. "The last several months of 2000 were particularly challenging, for Apple as well as for the rest of the industry," Jobs told the packed auditorium at the Moscone Convention Center.

"A lot of people have been saying that the PC is dying . . . or that it's become totally boring," Jobs said. "We think that the PC is evolving, just as it has. We believe that the PC is on the verge of its next golden age — the age of the digital lifestyle."

Jobs began the keynote with a glimpse into Apple's much anticipated OS X, its biggest operating system overhaul to date. Featuring protected memory, a new "aqua" user interface and symmetric multiprocessing, the open source OS X will be available on March 24 for $129. An avalanche of applications software is due to hit the streets in mid-summer, Jobs said.

"We're taking several weeks to make sure this thing is absolutely solid," Jobs said of the OS, which has been in beta release since September.

While delaying the release of OS X, which he had promised would be available by now in his keynote at last year's Macworld, Jobs unveiled four new PowerMac G4 models. Topping out at processor speeds of 733 MHz, the PowerPC G4-based systems are also offered in speeds of 466, 533 and 667 MHz.

"We've been coasting at 500 MHz for 18 months now," Jobs said. "But this megahertz myth has gotten out of hand. What matters most is the power of the overall machine, not just the power of the processor."

Featuring the ability to burn DVDs and CDs via what Apple dubs its "superdrive," the new PowerMacs also feature a new on-chip Level 2 cache and backside Level 3 cache in its top two high-end systems, as well as new high-performance graphics cards and a 4x AGP slot, a 133-MHz system bus, up to 1.5 Gbytes of PC133 SDRAM, PCI throughput of up to 215 Mbits/second, and built-in Gigabit Ethernet.

The 4x AGP slot is capable of transferring digital video data at up to four times the speed of the original AGP bus, Jobs said. The system features an Nvidia GeForce2 MX graphics processing unit and a focus on DVD authoring and digital music. The DVDs burned on the superdrive will play on a consumer DVD player.

"We're late to this party," Jobs said of the DVD features, "but we're going to be leapfrogging it." While older systems took 25x play time to burn a DVD, the "superdrive" will burn a DVD in only twice its playing time.

The top two PowerMac systems will be available in February, Jobs said, while conceding that there probably wouldn't be enough 733-MHz systems to meet demand.

Jobs saved the latest, greatest PowerBook iteration for last. Weighing a mere 5.3 lb. and measuring only 1-inch thick, the system features a 15.2-inch flat-panel display, and a five hour battery life. A 500-MHz notebook sports a slot-loading DVD drive and is manufactured out of titanium, "the same material they use to build spy planes," Jobs said.

Offered also in a 400-MHz model, the Powerbook G4 Titanium features 1-Mbyte backside Level 2 cache on the processor module, a 200-MHz or 250-MHz dedicated 64-bit backside bus, a 100-MHz system bus, integrated floating-point unit and 64 kbytes of on-chip Level 1 cache. For memory, the system features 128 or 256 Mbytes of PC100 SDRAM, and two SO-DIMM slots that will support up to 1 Gbyte of memory.