it means that there's 2 physical cores of the CPU and it's meant to improve multitasking abilities. Basically, you should be able to do more things at the same time with less drain on your system. RAM improves multitasking by meaning that you can have more programs open at the same time, but dual-core improves it more in the way of you can have multiple cpu-intensive programs running at the same time. Ie: you could be encoding video at the same time as watching a movie without notable slowdown of the system. Theoretically anyway. Long and short of it, unless you plan to multitask a lot or they are offered at a bargain price, a dual-core system at this moment in time is not an absolute necessity it just makes your system more future-proof.