Upgrade Dell Inspiron N5010 CPU

Questions:
I have a dell inspiron n5010 have an Intel Cor i3 M370 at 2.40GHz 3GB of DDR3 1333MHz ram and a 320GB hard drive. But recently it running very sluggish when i running Photoshop CS5, Battlefield 3, World of Warcraft, and Office Suites. And after defragged the hard drive and cleared up as much space, But it still runs slow. The questions is that, i am going to upgrade the ram to 6GM, and also going to upgrade the processor to i5 if it is neccessory.
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Apple A1286 , A1286 Battery
---------------------------------------------------------------------- Answers: It many wouldn't work any better with a core upgrade. I also see the i5 (quad core) uses a different socket then the i3.