New motherboard and processor?

My old motherboard and processor were both fried and was looking to buy some new ones. my old processor was core 2 duo 2.66ghz model and i had an intel motherboard to go with it. i am looking to buy a new processor (with a corresponding motherboard but nvm that) that is just a little stronger than my previous one. i understand core i3 is the newer generation but i want to know is there much of a difference in buying a core i3 or core 2 duo since it is more expensive. core i5 and i7 are out of the question since they are too expensive. so if you would kindly name a processor that fits me best