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No - it's not. Even an I3 530 overclocked should be "okay".
But, technically, most games released now are dual core +. Some (such as Re5, GTA4, crysis and so on) support more (such as 4 cores).
Many are using I5's, especially the 750's.
AMD aren't a bad option either, the X6's or the X4's.
Quad is future proofing, so i5 is more than enough. BC2 is definitely optimised for quads and I saw a significant increase when I upgraded from an [email protected] to rig in (same GPU). I expect future games to start using more than duals in the future. Seem to recall a feature over at toms hardware that indicated that tri core's were the sweet spot for gaming.
So i might as well stick with my Q6850 (@ 3.33Ghz) and just upgrade my GFX cards?