The Centrino is a combination of a CPU, chipset, and wireless hardware. The CPU is called the Pentium-M, which is not the same as the Pentium 4-M. Here, this link should clear up some details: http://www.pcworld.com/news/article/0,aid,109606,00.asp
What TravisS was saying is correct. From what I have read, the Pentium-M outperforms the Pentium 4-M. If you click the "I" next to that dropdown box he was talking about, it explains about the CPU.