In most laptops, you can upgrade the processor, but you have a very small selection of compatible processors you can swap out to. For the most part, they're the same processor at different clock speeds. Don't even bother swapping the motherboard out, it'll be cheaper and easier to just buy a new laptop. In other words, get used to the one you have, or buy a new one. Laptops really aren't upgradable, although there are some aftermarket notebook video cards on the market now.
I see that I got here a bit late. Seems to me that you just bought a new laptop and put it in your old case though to be totally honest. Glad it worked out for you though