How did you install the module? Judging by the first paragraph I assume that you downloaded it by hand and then unzipped it into c:\perl\lib\crypt\blowfish. That might work with some modules, but many require extra setup and initialization on installation. The easy way of doing that it to use ppm3 (assuming you are using ActiveState Perl):

ppm3 install Crypt-Blowfish
[download]

automagically downloads and installs the Crypt::Blowfish module (at least on my system). You should then be able to just put use Crypt::Blowfish in you script and it should work straight away.

Apologies if you've already installed and set up the module properly; I don't mean to sound rude or anything.

Cheers,
--Moodster