This package will help you install the latest Microsoft ForeFront Client Security definition updates.

mpam-fe.exe
Antimalware Full + Engine package (for x86, amd64, ia64)
Contains engine (mpengine.dll), mpasbase.vdm, mpasdlta.vdm, mpavbase.vdm, mpavdlt.vdm, mpsigstub.exe. 

mpam-d.exe
Antimalware Delta package contains AV and AS signatures.
Contains mpasbase.vdm, mpasdlta.vdm, mpavbase.vdm, mpavdlta.vdm, mpsigstub.exe.


Note: You must be running an x32-based version of Windows to run an x32-based version of Microsoft ForeFront Client Security, or an x64-based version of Windows to run an x64-based version of Microsoft ForeFront Client Security.