The P4 3.4E is not the same as the 3.4EE....definitely go for the 3.4E if the price is almost the same.
This shows a comparison of a 3.2C vs 3.2E (also 3.2EE included). The Northwood core (C) seems to be just slightly faster than the Prescott core (E) at lower speeds, but as clockspeed increases, the Northwood loses its advantage. Anandtech actually end up recommending the 3.2E...so if you can get a 3.4E for little extra cost, that would be my choice.
Of particular interest to you might be that the Prescott core was actually faster at encoding than both the Northwood core AND the Extreme Edition. :eek: