transferring I Tunes Library

Welcome to Apple Support Communities

You can do it by different methods, but the best is to use an external drive > http://support.apple.com/kb/HT1751?viewlocale=en_US&locale=en_US Do the "Restoring your iTunes Library" backup" in the iMac.

Apart from that method, you can use Migration Assistant, but it will create a new user with only the library

So drag it from the PC onto the iMac. If you don't have the two machines on teh same network, then put the library on an external HD and drag it to ~/Music. The ~ symbol indicates your home directory.