Best option is to use Windows Migration Assistant as Ralph noted.
Here's a better (updated) link to Windows Migration Assistant for Lion -> http://support.apple.com/kb/HT4796
Or if you only want iTunes (Migration Assistant let's you choose) copy the entire /Music/iTunes/ folder from your PC to /Music/ on the Mac.
FYI: A MacBook is not a PowerBook. PowerBooks were discontinued in 2005.