Do I need to apply both 32 bit and 64 bit versions of a .NET Framework update?

Question

There's a post-.NET 3.5 SP1 update which comes in x86 and x64 flavours:

The KB article is here:

List of the issues that are addressed by the Application Compatibility Update for the .NET Framework 3.5 SP1

There are two possible updates:

NDP35SP1-KB958484-x86.exe
NDP35SP1-KB958484-x64.exe

Will the 64 bit edition also update the 32 bit .NET Framework that's installed on Windows 2008/Vista 64 bit?

Answer 1

Your CPU is either 64 bit or 32 bit.

Do you have a 64 bit CPU? Install the x64 flavor.
Do you have a 32 bit CPU? Install the x86 flavor.

Answer 2

To expand on "matt b"'s answer, the 64-bit .NET Framework updates that Microsoft provides will always update both versions of the framework (native 64-bit and the "WOW64" 32-bit framework).