What? *nix's process scheduler is horrible in comparison to Windows.
The reason you don't need to screw with processor affinity on *nix is because you don't have a PB Driver trying to scan you entire harddisk all the time, thus creating more threads whilst still accessing the originals within ET.exe on the original core. Switching ET.exe (and thus it's dependents, ie. PB) to one core speeds it up because there's no cross-core access between PB and ET.exe itself.... IF you disable PB and leave affinity alone, since ET is single threaded, it has exactly the same result as setting affinity.