It's not a great one... you will need to have some luck to reach 2 GHz. You can search the OC database on Overclockers.com to see what OCs are reached.
My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on
If you want a good overclocker, get an Athlon 1700+ Throughbred core. These overclock extrmely well. Stock is at 1.47 GHz. but you can clock these to 2.2 or even 2.3 GHz with good cooling.