If you are running the 32-bit RPM on 64-bit Windows, you may run into problems running a program you might want to use in a filter action, just because you’re launching the program from a 32-bit program (RPM, of course).
This page talks about some of the issues running programs in a mixed environment.
Take it from someone who remembers that upgrade, it’s better to go all 64-bit when you switch over to 64-bit Windows.
The user interface shows you whether you are using 32-bit or 64-bit RPM:
Note this says "x64" which is how you know it’s 64-bit.