QUOTE(Aggroboy @ May 1 2010, 12:08 PM)
WoW doesn't use the extra cores in i5, so you essentially have a slower main proc unless you OC.
An OCed dual-core will give better bang for buck in this game.
the last few patch have WoW ultilizing quads natively by default.
prior to that patch, you need to manually check affinity for the remaining cores other than 0 and 1 (your 1st and 2nd dual core, basically)
less work on task manager > wow.exe > affinity > check 2 cores > ok

so yeah, WoW does ultilizes quad cores, any more, i wouldnt know since i run on quad only