SP1 is supposed to put an end to Windows XP theft
Service Pack 1 for Windows XP, which is currently in beta, is intended to put an end to the flood of pirated copies, at least in the meantime. Among other things, the update will ensure that the 'corporate keys' of the cracked versions that were previously used for activation no longer work.
In order to get such a system up and running again, new keys are required that contain generated by a modified algorithm. However, it will no longer be possible to use such a key illegally on an illegal copy, as the system will now recognize the required mix of corporate and pro/home versions. The only question that remains is how Microsoft intends to persuade/force users to actually install SP1. Thanks to 'yoda' for the tip.