something not confirmed but i think the flop rate of cpu can provide fair comparision of cpu performance coupled with cache size and other things but processrs have grown complex and only speed along will not prove the capability..
like p4 mobile get its ass kicked by centrio at almost half clock rates
best thing is to search on the internet or the reptuable manufacturers should attach the bench mark results of some industry proven testing methods but the truth is day by day it getting harder to evaluate cpu and system for performance. well u can evaluate a cpu alone but then again the system performance depends on other factors like hard disk and ram and stuff.. a fast processor can be flushed down to toilet if u have a slow ram or hard disk