How do pentium m match up with today's atom processor?how does lenovo thinkpad x31 match up w/ current netbook?

pentium m laptops are 12" under 4 lbs and can be bought used or refurbished for under $150-$200. lenovo thinkpad x31 battery life is 6 hrs on 6 cell (that is on highest energy saving and minimum use) but aren't most netbooks around 5 hrs today? Besides the fact that these laptops can only be bought used or refurbished and that old batteries might have deterioted. If i dont mind used/refurbished do these laptops pretty much achieve the same functions of current day netbooks? or is there something advantageous in current day netbooks that I am not seeing?