Apple today released a public beta of Boot Camp, a collection of software that will allow Windows XP to boot on Intel-based Macs. The final version of Boot Camp will be available as a feature in the upcoming Mac OS 10.5 "Leopard".
Once you've installed Boot Camp, you will be able to hold down the option key at startup to choose between Mac OS X or Windows XP. You must supply your own copy of Windows XP, which will require a second hard drive partition, and Apple will not offer technical support for installing or running Boot Camp or Microsoft Windows software.
An Intel-based Mac with the latest firmware and OS X updates is required. Boot Camp includes Mac-specific drivers for Windows for graphics, networking, audio, Airport wireless, Bluetooth, the eject key on Apple keyboards, and brightness control for built-in displays.
The public beta of Boot Camp can be downloaded now, free of charge. An Apple press release says it is available on a trial basis for a limited time but doesn't specify the time limit. (We suspect the trial is designed to expire when OS 10.5 "Leopard" becomes available with the final version of Boot Camp built in.)
More details are available at Macworld and Macintouch.