Although 64-bit Windows platforms support both 64-bit and 32-bit applications, the OpenAFS Service installed on the machine must be 64-bit. The 64-bit installer contains only 64-bit executables. In order to support 32-bit applications it is required that a separate 32-bit OpenAFS Tools set be installed. This is especially true when the IFS redirector is in use as the 32-bit Network Provider DLL must be installed in order for 32-bit applications to access drive letters mapped to \\AFS.
OpenAFS on 64-bit Windows benefits from the lifting of the 2GB process memory restriction that is present in 32-bit Windows. Without this restriction the AFS Cache File can become arbitrarily large limited only by available disk space.