You're trying to compare two totally different generations of processors. As other's said, there is no comparison.
As for the duo, that's intel's name for duel core. Not too many applications actually utilize this yet, but it does help out with some things. You can also divide up the loads between the cores. Now, this doesn't give you twice the speed of a single core. Actually, with many applications, single cores are faster, unless the software utilzes both cores as I mentioned.
Edit - Ah, and I'm a bit slow ;P
With your last comment about the speeds, look at other processors speeds. The efficientcy of processors has gone up a good bit, so many more operations can be done per clock. So, that's why 2.4GHz processors can beat 3.8GHz processors
