If going from one 5.6 version to another, or from one 5.8 version to another, you can copy modules. However, you half-copied a module, copying it's XS component without copying its .pm component or vice-versa. You should have restricted yourself to non-core modules (site/), for starters.

If you don't mind some of your modules getting upgraded, you would probably have been better off copying c:\perl to c:\perl5.8 then install over c:\perl5.8.