In all honesty at this moment in time, a dual core is fine for running pretty much everything as long as you got the clock speed, triple core and quads are all very good for the future but right now there not really necessary, not even for gaming on games such as crysis, GTA, Mass Effect, etc.
~Specs~
Q6600 @ 3GHz
OCZ HydroFlow MK1 Waterblock (15-18c idle is awesome)
Gigabyte G31M-ES2L
EK CoolStream 120mm Radiator
XSPC 5.25" Reservoir&Pump
NVIDIA GeForce GT240 512mb
OCZ 2GB*2
500GB Western Digital (OS)
1TB Samsung (Backup)
XCLIO Propeller
Windows 7 Professional x64
Q6600 @ 3GHz
OCZ HydroFlow MK1 Waterblock (15-18c idle is awesome)
Gigabyte G31M-ES2L
EK CoolStream 120mm Radiator
XSPC 5.25" Reservoir&Pump
NVIDIA GeForce GT240 512mb
OCZ 2GB*2
500GB Western Digital (OS)
1TB Samsung (Backup)
XCLIO Propeller
Windows 7 Professional x64