trueheart78 said:Benchmarks From AnandTech for Notebooks.
Core Duo vs Pentium M
http://www.anandtech.com/showdoc.aspx?i=2663&p=1
Core 2 Duo vs Core Duo
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2808
Good to have them all in the same graph

It's safe to say the biggest increase comes from Pentium M going to Core Duo.
Of course, I'll take every performance increase I can get for free