CPU Suggestions

So, surprisingly I'm going to upgrade my fathers laptop for him. The freaking Foxconn terrible support lead me to forums. I only know that the socket is a 478MN. I need some suggestions for CPUs to upgrade to as the current CPU is a P8400, i think.... 2.26ghz. Also, I was wondering if the 478MN socket is just the same as a 478 socket. Thanks please discuss.