Storable has an XS component, which basically means C (or possibly other?) code that needs to be compiled to make the module work. CL is the name Microsoft C Compiler, which is what perl tries to use by default on win32 (or atleast activestate tries to use it, I suppose perl tries to use whatever it was compiled with). Storable comes by default with 5.8, so I'm suprised you don't have it. If you want to manually compile it you'll have to get your hands on the same compiler that your perl was compiled with (vc6 works fine for activestate for everything I've tried), or find another compiler and compile perl yourself.