While you can do it, I'm not sure you should do it. The 4 core options use quite a bit more power, which means more heat. I doubt your laptop has the capacity to get rid of that extra heat and overheating will be an issue. So the only options are dual core, like you already have. Going from 2.3 GHz to 2.8 GHz is not going to get you that much ... just my opinion. If your just looking for a fun project, go for it.
While you can do it, I'm not sure you should do it. The 4 core options use quite a bit more power, which means more heat. I doubt your laptop has the capacity to get rid of that extra heat and overheating will be an issue. So the only options are dual core, like you already have. Going from 2.3 GHz to 2.8 GHz is not going to get you that much ... just my opinion. If your just looking for a fun project, go for it.