It takes 578mhz to do one w/u a day. Therefore that would mean an 867mhz would do 1.5 a day (accurate, thats what my PB does) and a 266mhz would do one every 2.1 days, also accurate. Someone compare my equation to their computer. All you do is take your CPU speed and divide it by 578. It *should* give you roughly the w/u you complete in one day.