the idea of an ultraportable is that it is, ultra portable (surprisingly enough). To be ultraportable, it has to have a small screen to minimize size, has to be light, and has to have a long battery life. Long battery life means using components like LED displays, flash memory, and ultra-low voltage CPUs. ULV chips don't go much higher than 1.5GHz, and are usually single core (correct me if i'm wrong here). To get the battery life you want, you're going to have to make some sacrifices in terms of performance.
If it's a 13.3" MBP you're talking about, sure, they can handle 2.4GHz CPUs, 256MB GPUs, 4GB RAM and a Superdrive, but the battery life in those machines is pretty poor.