you question doesn't make much sense. there is no intel M450 socket, but there is a i5 540M CPU, and your model does come with that CPU and that is the best CPU your laptop is compatible with. you can't upgrade to an i7 so the only way to upgrade your CPU would be to buy a new laptop. sorry. that's what sucks about laptops, they aren't very upgradable at all.
I have a similar Asus laptop and I can tell you now you are pretty much stuck. Your I5 you have now is about as good as you are going to get. Your (our) Asus laptop motherboards can't accept the I7 so as someone else said the only way to get something better is to get a new laptop.