That is right, E5200 is a very very good CPU for your money. faster than E4xxx series and more efficent since it's 45nm. OC's very well. If you have money go for E8400, mighty CPU for gaming, or Quad Core for jobs such as video editing, Q6600
Currently the only real difference between Pentium dual core and core 2 duo is the cache size. Example, E6300 is a pentium dual core, it's the same clock speed as the E7400 however it has 1mb less Cache. The E6300 has 2mb, the E7400 has 3mb. All ''Core 2 duo's'' have atleast 3mb cache.
The Core 2 Duo E8400 is still really overpriced. $168 for a dual-core processor is a rip off.
If you are going to spend that much on a processor I would go with a Phenom II 945 Quad-Core, an Intel Core 2 Quad Q9400 for $190 or an Intel i5 750 for $200.