One of the 'big' features discussed in early speculation of Windows Vista SP1 was the kernel upgrade, which was supposed to bring the operating system into line with the Longhorn kernel used in Windows Server 2008. And yet with Vista SP1 going RTM, there hasn't been so much as a peep from Microsoft about the mooted kernel update. Has it happened? Well the answer is yes it has. The version and build information of Windows Vista SP1 and Windows Server 2008 (RTM) are exactly the same as each other. And yes, Vista's kernel has been replaced. Windows Vista pre-SP1 is Windows version 6.0 build 6000 (6.0.6000) whereas Windows Vista SP1 RTM is version 6.0 build 6001 (6.0.6001) – the same as Server 2008.

The whole thing is still quite interesting. You can tell what build of Windows you're running by a variety of means: if you open a Command Window it will immediately tell you what version you have or go Start --> Run --> winver or check out the properties of C:\Windows\System32\NTOSKRNL or open Regedit and navigate to HKLM\Software\Microsoft\Windows NT\Current Version.  All these methods will give you an idea of what version and build of Windows you're running, although the last two give more detailed information.

In other news, Microsoft have made available a document outlining the various changes made to Windows Vista in Service Pack 1 on Microsoft Downloads. This document provides more detail about the notable changes made to Windows Vista in Service Pack 1, which were focused on addressing specific reliability, performance, and compatibility issues, supporting new types of hardware, and adding support for several emerging standards.