Parallels: Run Windows XP, Linux & any other OS simultaneously with Mac OS X
Parallels Workstation is the first virtualization software designed to work with Intel-based Apple computers including the MacBook Pro, which allows the you to simultaneously use Windows, Linux and any other operating system at the same time as Mac OS X.
Unlike the Boot Camp from Apple, Parallels let's you work with all these operating systems without a dual boot; sort of like Microsoft Virtual PC and other virtual PC emulation software, but due to native virtualization it's claimed to offer pretty much the same speed as running it natively.
We haven't yet downloaded a copy or verified the claimed, but it's available for free from http://www.parallels.com/en/products/workstation/mac/. Give it a trial, and let us know what you think.