The c-orb performs like crap, despite what reviews say about it. Check my sig for more details, but for example, the anandtech test c-orb claimed the t-bird/950/1.85v was running at 47C, when core temp is actually well into the 60s.
I'd be very, very careful with a c-orb and i'd set a limit of around 950/1.8, or 1ghz 1.75V with a c-orb use. Past that, and you're pushing into extremely hot core temps. you'd also be better off with one of the taisol units at the same price range.
Mike