First off it appears there are in fact 2 versions of the NSLU2 one being 266MHz and an underclocked one running half speed at 133MHz. You can find out by telneting to your box and doing the old cat /proc/cpuinfo command. If you’ve got the underclocked version there is lots of info here http://www.nslu2-linux.org/wiki/HowTo/OverClockTheSlug on how to overclock it. From what i’ve read it appears models manufactured after May 2006 run at 266MHz.