i would say that the pentium-m/centrino type machines are very good.
you get the power of pentium 4, but the ace that the pentium-m has is battery life.
to answer your original question, the battery life is at least 3 hours and the performance is very good considering the battery life. i dont understand your last question though.
if you want a good centrino machine, but dont need good graphics, get an ibm.
if you want good graphics with centrino, get a machine from vendors such as dell, compaq/hp, and gateway.