My Compaq (Don't start complaining) overclocks very well. A Presario 1247 with a AMD K62-400 Mhz. I put a K6-III 450+ in and am running at 550Mhz no problems at all. The board has voltage setting from 1.4V to 2.2V, FSB settings of 66,100 and 133. and Multiplyer settings of 4.0 to 5.5 that I could figure out. Not bad for a Crappy Compaq laptop.
edit - All these settings are adjustable with dip switches