I'm not sure what constitutes the Microsoft paradigm these days - it's many years since I last touched it, so I don't really know what your background is.

Perl is most at home on Unix, and it shows in the language. If you're not familiar with Unix, then I think you should start there. Not that I can recommend a good book, cos I disremember what I used. Then, as others have said, check out the Llama book. I don't think anyone suggested Effective Perl Programming, which is an old but excellent book. It will help you learn to program in a perlish way instead of just thinking VB or C# in your head and translating it directly. Given that you're an experienced programmer, you'll probably not need the Llama for very long, so consider reading it on Safari instead of in dead-tree format.

What you should move on to after that depends on the tasks you've got to do.

Don't forget about the online documentation. perldoc -f functionname to get the docs on a built-in function; perldoc Module::Name for the docs on a module; and perldoc -q keyword to search the FAQs. That last one is particularly useful and not as well-known as it should be.