Hello,
What I can tell you is that for a laptop, you need a "mobile" processor. a mobile processor means that your proc won't run at 100% of its possibilities everytime for energy purposes. There are maybe other peculiarities, but I think it's the main.
About Centrino... Intel =

for wireless. With their dedicated 802.11 chipset, they were the worst (or at least one of the worst). So I don't think they improve their wireless chipset by integrated it with their processor...
Oliv'