Hmm. Its a bit hard to determine which one is faster as the P4 D used to be Intel's premium processor while the newer Core 2 Duo E4300 in Intel's hierachy of things is between a Celeron and a Core 2 Duo E6000. I'm gonna explain all this as requested, but its going to be a bit technical...

Anyways, for rendering you would want lots of cache and the Core 2 E4300 has more L1 with a lower access latency than the P4 D but has only half the L2 cache of the P4 D. I'm not sure of the exact specification of the Core 2's L2 cache, nor if there are any differences between the E6000 and the E4000, but I think that the Core 2 has a more effiecient cache with higher bandwidth than the P4 D, (256 bits vs. 128 bits).

Onto the actual processor, the Core 2 Duo is a four issue processor, it issues a maximum two integer and two floating point instructions a cycle per a core, unlike the P4 D which is three issue (two integer, one floating point). So with Maya, which is very floating point intensive, the Core 2 sounds like a better deal than the P4 D, except for that floating point performance is heavily dependant on the cache, which the E4300 has little of. Also, the Core 2 Duo can execute certain types of commonly used instructions faster than the P4 D, and Intel did some complicated stuff to make the processor more effieicent.

Onto the FSB, its the same on both processors so you'll get the same performance in that area... So its time to decide which one is better. This is my opinion: The Core 2 Duo 4300 is better at executing things, but since its clock speed is 1 GHz slower than the P4 D and becuase there is not enough L2 cache for the processor, which will demand a lot of data to process, performance is greatly reduced.

Factor in the slow bus designed for the P4 to feed the more advanced cache in the Core 2 is going to even reduce performance more. I can't really say which one will be faster becuase their advantages and disadvantages sort of cancel each other out if you know what I mean.