Run this little app, set up a new profile. (right click in the little white window, and select add program).
Name the profile in the top bar, then click the browse button, locate the BTR executable and select. Can set priority too if needed. Then, go to the SMP tab and you can set which CPU(s) it will use. Save profile and then whenever you launch the game you run WinXP launcher and double click your profile. No need to alt-tab and manually set affinity each time.
Added plus, at least for me, the game launches/save loads much faster when set to a single core from the start.
