Since it doesn't specify the model, I would say you should be good to go.
The 2 Ghz Core 2 Duo is more than a little bit better than a 2.4 Ghz P4. What they SHOULD have said is 2.4 Ghz P4 or better. That would cover any Core 2 Duo as well.
The processor you bought is one of the best on the market, it should be no problem at all.