Apple has upgraded its PowerBook line-up of professional portables, by swapping the DVD-ROM-only drive for a slot-loading combination DVD-ROM/CD-RW drive.

The slot-loading Combo drive plays CD-ROM, audio CD, DVD video, DVD-ROM and DVD-RAM discs.

Apple's DVD player, iTunes 2 digital-music program and Disc Burner software come pre-installed on all PowerBook models.

RAM doubled, too Apple has also doubled the memory of every machine (previously this was only to have held until the end of this year). The now £1,699 550MHz entry-level model (up £100 in price) now has 256MB of RAM, and the £2,199 667MHz model (price remains same) boasts 512MB of RAM.

Greg Joswiak, Apple's senior director of hardware product marketing, said: "The titanium PowerBook G4 is one of the most successful notebook computers of all time, and we are making it even better."

Options for the 'Ultimate' build-to-order model include: 48GB hard drive, 1GB of RAM, AirPort Base Station and Card, and the AppleCare Protection Plan.