Microsoft delays the general roll-out of the Windows XP SP3.

Microsoft encountered apparently a compatibility issue between Microsoft Dynamics Retail Management System (RMS) and the XP SP3 update. The problem even exists with the Vista SP1.

Microsoft plans to put filtering in place shortly to prevent Windows Update from offering both service packs to systems running Microsoft Dynamics RMS. Once filtering is in place, Microsoft is expecting to release Windows XP SP3 to the web.
MS is also working on a fix to solve the Microsoft Dynamics RMS for those of you who already deployed XP SP3.
Via this post from Microsoft's Chris Keroack.

We reported yesterday that links to download the XP SP3 update surfaced. These links are still live. I am waiting though until Microsoft gives their official go. I do not want to wreck my ultra-stable XP system.