This is undoubtedly a duplicate question, but my search skills have failed me.
How can I determine whether an app is 64-bit or 32-bit on Windows?
Ideally, I'd like to be able to do this on both 64-bit Windows XP and 64-bit Windows 7.
EDIT: thanks for the responses. Is there a way I can do this when the app is not running? For example, on Linux we've got "readelf"--a command line util to inspect binaries. Is there a comparable tool on Windows?