There are much confusion when Microsoft releases Windows Vista Service Pack 1 RC Refresh 2 (RCR2) was released, due to the fact that the supposedly ‘release candidate’ does not bear the “Evaluation Copy” watermark as with previous beta release, no more expiry date, and comes with a RTM fingerprint 6001.18000.x86fre.longhorn_rtm.080118-1840 and 6001.18000.080118-1840 which similar to final build number of Windows Server 2008 as its build version.

Thus when Microsoft officially announced the available of Windows Vista SP1 RTM on 4th February 2008, it’s one of the major contention point that among Windows Vista enthusiasts on whether the SP1 RCR2 is actually the real SP1 RTM, and whether there is any change been made to the final SP1 release compared with SP1 RCR2 release. One of the most wanted asked question and most eagerly awaited answer is whether Windows Vista users can safely install Windows Vista SP1 RC Refresh 2 without any implication.

Now Microsoft finally offers some insight into the relation between SP1 RCR2 and SP1 RTM. Indeed, both is the same, but only on SP1 RCR2 distributed via Windows Update (WU). Geek’s Anatomy (dead link) confirmed from the Jeff DaVos, one of the many Windows Vista SP1 beta program leaders in Microsoft Connect beta newsgroup that Windows Vista SP1 build 18000 released (via WU only) is indeed the RTM build, and the build didn’t change at all from the time been released to final sign-off on Monday morning this week (February 4th).

What you got is what we’re all running our Vista machines here internally – we definitely RTM’d.

It’s unclear why the RTM version from RC Refresh 2 is limited to WU release only, as now there is plenty of standalone SP1 setup package available for download, but obviously these installers are not sanctioned officially, yet. There are rumor for another ‘official Windows Vista SP1 RTM’ release date on February 18 or 19, 2008, which may be the date to confirm the final standalone installation package for Windows Vista SP1 RTM. Anyway, for those who can’t wait till mid March for official roll out of SP1, based on above statement, install Windows Vista SP1 RCR2 via WU to get the real SP1 RTM.