Apple made rumours official this week when it announced upgraded versions of its mobile computers — the high-end PowerBook G4 and the consumer-oriented iBook.

The new PowerBook G4 comes in two models, built around 550MHz and 667MHz PowerPC G4 processors. The speedier device offers a new system bus — that is, the path by which data is routed around the motherboard — running at 133MHz. The 550MHz portable, on the other hand, uses a 100MHz bus.

Upgrades to both PowerBooks include a 4x AGP (accelerated graphic port) video system and a gigabit ethernet port. Each system comes with a slot-loading DVD, 15.2in screen, 56Kbps (kilobits per second) modem, USB and FireWire ports. A slot-loading CD-RW is available as an add-on, marking the first time this feature has been available for the PowerBook G4.

The 550MHz model comes standard with 128MB of RAM, 20GB hard disk and an integrated antenna for Apple's AirPort 802.11b wireless ethernet system. The 667MHz system offers 256MB of RAM, 30GB hard disk and comes equipped with an AirPort card and antenna.

Both systems can be expanded up to 1GB of RAM and can be customised with a 48GB hard drive. Each system comes preloaded with both MacOS 9.2.1 and MacOS X 10.1. The 550MHz model costs around £1,395 plus VAT, while the 667MHz model runs in at just over £2,000 plus VAT.

The new iBook (pictured) line comes in three models, built around a 500MHz or 600MHz PowerPC G3 processor. All models offer a new 100MHz system bus and 128MB of RAM as standard. The portables also include a 12.1in screen, ATI Rage Mobility 128 Graphics chip with 8MB of RAM, a 56Kbps modem, onboard ethernet, USB and FireWire ports and an integrated AirPort antenna (though the AirPort networking is not included). All systems are preloaded with MacOS 9.2.1 and MacOS X 10.1.

The low-end 500MHz model offers a 15GB hard disk and costs around £900 plus VAT. The high-end system, sporting a 20GB drive and a combination DVD-ROM and CD-RW drive, retails for around £1,200 plus VAT.