transfer iTunes from Windows 7 to OSX
Just copy over the "iTunes" folder which should be located under your user's music/my music folder. If you can't find a folder there named "iTunes", you must have moved it to another location. To check, go to iTunes preferences and read the location under the "Advanced" tab.

Using any means wether it be network file transfer or using a USB Drive, move the "iTunes" folder to the "Music" folder in your mac's user account