How can I tell which version Service Pack I have installed?

A. A. When a Service Pack is installed using the normal method (e.g. notjust copying the files to a build location) the service pack version is enteredinto the registry value CSDVersion which is underHKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersion.

The value is of the formal "Service Pack n", e.g. "ServicePack 4" but can have extra information if it is a beta or releasecandidate, e.g. "Service Pack 4, RC 1.99".

To check this from the command line you could use the REG.EXE Resource Kitsupplement 2 utility:

C:>reg query "HKLMSOFTWAREMicrosoftWindowsNTCurrentVersionCSDVersion"
REG_SZ CSDVersion Service Pack 4, RC 1.99

Make sure you put the value in double quotes (").

An alternative is to just run WINVER.EXE which will tell you your currentbuild and Service Pack version. You can also use WINMSD.EXE or Help/About inExplorer.