One of the questions many people have is whether these Mac computers now support Windows and Linux because they run on x86 Intel hardware. The answer is yes.
Apple even said during an interview yesterday that the company won't deliver or support Windows itself, but it won't preclude people from loading Windows on the machines.
However, personally I think it isn't smart to buy a MacBook Pro if you're planning to run Linux or Windows XP and there are a couple of reasons for this:
The first reason is because these computers are designed for Mac OS X - and not for Windows or Linux. Running Windows XP on it will be possible but don't expect an optimal work situation. The MacBook Pro for instance doesn't have a right mouse button. So unless you connect a mouse to your MacBook Pro you won't be able to use the right click functionality. (Of course there are other solutions - like tapping on the trackpad - but those solutions aren't really comfortably).
But the main reason why you shouldn't buy a MacBook Pro to run Windows XP on it is the price. Unless you really want an Apple notebook for the design or to run Mac OS X there isn't really a point because they are more expensive. Overall, other manufacturers will give you more value for less money.
The cheapest MacBook Pro will cost you $1,999. For that price you'll get a notebook with a 15.4-inch LCD display, 1.67GHz Intel Core Duo processor, 512MB RAM, 80GB HDD and the ATI Mobility Radeon X1600 GPU.
For the same price Dell offers the Inspiron E1705 which has a 17-inch LCD display, 1.83GHz Intel Core Duo processor, 1GB memory, 80GB HDD and the NVIDIA GeForce Go 7800.