As an aside why is there a Learning Perl and a Learning Perl for Win32?
There really shouldn't be, any more. We worked hard to eliminate the Unix-knowledge bias for the 3rd edition of the Llama. But when I suggested that this signaled the end of the Gecko book, the O'Reilly staff said "why stop printing a book that sells?".
So, the Gecko continues to sell, but in an ideal world, it'd be gone by now.
When we teach a "Learning Perl" class, we always use the Llama, regardless of the mix of the students between 100% Unix and 100% Windows. I don't think I've ever even ordered the Gecko for a class.