I use mostly use Asusprobe, because it came with my mobo, but sometimes MBM is more accurate, because it reads the core directly, sometimes i doubt if Probe does that, i only think probe reads the external heat of the CPU, and it's more useful to know the core clock, because you can OC your Cpu after the core instead of the external heat... so now i'm using the MBM moniter..
my regards
Philip