The best way i can explain a quad core, is that the processor will simply be able to multi-task better, it wont quadruple the speed. The intel i5 520m is dual core BUT has 4 threads (Thanks to hyper threading), though it will still outperform the AMD (If not by much, but it still will outperform). If you were only using this for gaming i would recomend the AMD but for converting videos, the intel is the way to go.