The key file is the library.itl file. This is the file iTunes uses to store all the information it presents to you when you open the program. Well, there's also a few other library files as well as the artwork folder, but the .itl file is the center of it. You don't say whether or not the PC has its own library with unique content, or if you are trying to duplicate the library for both. If the PC library is empty try copying the whole iTunes folder (which contains no media according to you) to the PC, then start iTunes with the shift key held down and guide iTunes to the new library file set (or copy it over the one currently on your PC and just start normally).
What are the iTunes library files? - http://support.apple.com/kb/HT1660
More on iTunes library files and what they do - http://en.wikipedia.org/wiki/ITunes#Media_management
What are all those iTunes files? - http://www.macworld.com/article/139974/2009/04/itunes_files.html
Where are my iTunes files located? - http://support.apple.com/kb/ht1391
iTunes: How to move [or copy] your music [library] to a new computer [or another drive] - http://support.apple.com/kb/HT4527 - a somewhat bewildering and not always easily understandable set of options.
Windows users see tip at: https://discussions.apple.com/message/18879381
It was a fresh install of Windows to make iTunes available 24/7 even when my MacBook is turned off. I used to library file copy method to transfer the I ibrary from a windows virtual machine to my MacBook Air last week. when I started having issues because the MacBook kept disconnecting from the network share and not being able to access my library from other devices when it was off, I decided to install Windows on a physical machine with a wired network connection to solve those problems. after I installed ITunes on the Windows box, I copied the contents of my MacBooks iTunes folder to the Windows folder, started ITunes to let it update the library. It had missing links for almost all of my media files . I changed the library location to the network share, and most of the 'missing link' icons next to my songs disappeared.
there are still missing songs in the Windows iTunes library, but overall I'm happy with how it turned out. the minus is that I have to run another machine ( and Windows at that, yuck!) to make my iTunes library available at all times.
not pertinent , but I plan on buying a nice IBM M1015 raid controller and virtualizing my FreeNAS System and windows system so that they can run on a single machine.
that will happen later on down the road.