Corporate Vice President of Microsoft Windows Product Management, Mike Nash announced that official final version of Windows Vista SP1 (Service Pack 1) RTM has been released. But ‘officially released’ is probably applicable to selected users only, and majority of users will have to wait one more month.

Windows Vista SP1 will be available will available through Windows Update in mid-March. But don’t pin your hope too much if you’re using non-English version. The initial roll out will be limited to English, French, Spanish, German and Japanese editions of Windows Vista only. Windows Vista users can choose to let Windows Update detects and installs SP1 automatically, or for those who can’t wait, download the standalone full SP1 setup package from Microsoft Download Center on Windows Vista users who don’t care and let Automatic Updates to do its job will only start to get SP1 from mid-April, which still limited to 5 languages above.

However, even if you’re using one of those 5 languages, you’re not guaranteed to be able to automatically see Windows Vista Service Pack 1 in Windows Update. This is because Microsoft has identified an issue with a small set of device drivers which do not follow Microsoft guidelines for driver installation, and will have to reinstall after SP1 is installed to avoid problems. As a result, to improve user experience, Microsoft requires those device drivers to be updated before delivering SP1 to system with these device drivers installed.

The rest of SP1 remaining languages will RTM in April through Windows Update and Microsoft Download Center. Other channels of delivery for SP1 RTM including integration by OEMs to new PCs running Windows Vista with SP1 pre-installed, and retail DVD product of Windows Vista with SP1. Both expected to be available in probably next month onwards. DVDs for corporate and enterprise customers with Volume Licensing program will also be distributed.

It seems like Windows Vista SP1 RC Refresh 2 is the version that RTM (Microsoft has confirmed Windows Vista SP1 RCR2 from WU is indeed RTM). Both has version build of 6001.18000.080118-1840. If you believe and bet that both are the same, you can now download and install via Windows Update or BT torrents.

As of mid April end of March, Windows Vista SP1 for 5 core languages has been released, while Windows Vista SP1 all languages, 32-bit and 64-bit, has also available available for download while all 36 languages of Windows Vista SP1 will be released early April. Both copies from OEM Partner Center has earlier leaked.