Microsoft released Windows XP SP3 RC2 Refresh which has a build version of 5.1.2600.5508. There are a lot of speculations and discussions on whether this RC test version is indeed will be released to manufacturing (RTM) to become the final release version for Windows Vista SP3, much like what happened to Windows Vista SP1 RC Refresh 2 (6001.18000) was directly turned into final build for Windows Vista SP1.
However, a sharp eye Windows XP enthusiast has pointed out that the final build version number for Windows XP SP3 is probably 5.1.2600.5573 when SP3 is released, based on file version information that Microsoft published on a Knowledge Based article.
As shown in the figure above, which is from KB951126 which address problems on multiprocessor computer running Windows Vista or Windows XP stops responding on a black screen after resuming from hibernation, the Windows XP user strongly believe that the final build version for Windows XP SP3 is 5.1.2600.5573.
However, taking a look the the build version for the files for Windows XP SP2, it’s 5.1.2600.3344, and not supposedly 5.1.2600.2180 which is the exact version for Windows XP SP2 when it’s released. So, in this case, it may be Microsoft increases the build version for these affected system files higher than the service pack version to reflect the update on the files been done after the service pack is finalized.
Based on such assumption, if 5.1.2600.5508 is indeed not a RTM ‘release candidate’, then it’s highly likely then build version of Windows XP SP3 final release will be between 5.1.2600.5508 and 5.1.2600.5573.
Update: Windows XP SP3 has build number 5512, making its version 5.1.2600.5512.