I'd like to check if a process is running in 64-bit or 32-bit mode. How can I do this? Process Explorer will tell me if the Image is 32-bit or 64-bit, is this what I should be looking at?
Just to add to this old answer, yes use Process Explorer. You can right click on the columns and select Image Type to show which processes are 32 bit and which are 64 bit. Run Process as Administrator to see some services.
Unlike in Windows 7 task manager where 32-bit processes are shown with
*32, in Windows 8 and 10 they'll be shown with
(32 bit) at the end. No need to go to the Details tab and add another column!
In compact mode they're shown in the same way, but in less detail compared to the Processes tab and Details tab