For those of you trying to get your hands on Microsoft Windows XP Service Pack 3, I found this direct link to Microsoft for the update. This should guarantee that everyone that wants it can get it and that you are getting the real deal.
*Update* The file linked has been changed. You can try this link and search for better copies but it is obvious MS wants you to wait until April 29th.
Please take this as a warning I attempted to install service pack 3 today and while the installation went very smooth without any errors I was unable to get back into windows upon restart, I was welcomed with a BSOD without any description of what went wrong. After running a scan with chkdsk it revealed an error with my system files. I highly suggest anyone still runing WindowsXP please wait until the official release date or when it becomes readily available through windows update.
I was lucky to be able to restore my previous installation through the installation cd without any loss of files or progams, however with any restoration some programs did not work or function correctly and required them to be re-installed. Windows update was also a problem as it thinks you need to be updated it constantly prompted me to install each time all attempts failed to, it eventually stopped prompting me to install any of the updates.
Install at your own risk and considered yourself warned, while my experience might be an isolated incident I felt that people should be aware that potential problems can arise.