what better beetween amd opteron dc or phenom 2 x4

[jontcold]

i wanna change my amd 5000+ x2 2.6ghz with 3gig 800 mhz

i asking what should i chooses opteron or more expansive but i dont really care if is very more powerful and you could put 2 cpu dual core
and does dolphin support 2 dual core

i really dont know what better and why thx for advice