there are a number of different ways to set you affinty i assume you want to set it cuz some of your games arent working right this happened to me the dual core ****es me off sometime and you can do it from the task manager i found that only somewhat affective there is a program to automatically do everything for you http://www.majorgeeks.com/WinLauncherXP_d870.html
I have not tried the above utility yet, but as I suspected the affinity assignments to stay if you close the program and restart. Does the above program let you do that or does it have to be done EVERYTIME you use that program?