Transferring your iTunes library from one computer to another is a very simple task. The trickiest part may be in connecting the two computers in the first place. Take a look at How to Set Up Your Network for PCs and Macs to find out more.
If you cannot connect the two computers, ideally by gigabit ethernet for example, you can always use an external hard disk. Copy the iTunes folder onto the disk, remove disk from first PC, attach to second PC, copy from disk to the correct place on the second PC.
How to transfer your iTunes library from one computer to another
Finding your iTunes library:
Finding the iTunes Library is simple enough. On a Macintosh, you’ll find a folder named iTunes in ~/Music. On a Windows PC, it’s in C:\Users\yourname\My Music.
Microsoft confusingly gives this directory two different names, depending on how you’re viewing it. You may also find it from a Windows 7 Explorer sidebar under Libraries\Music.
Copying your iTunes library over a network
To copy your iTunes library, drag and drop this folder from one PC to the other.
If you have connected the two computers by Wi-Fi and have a large music collection, expect a long wait.
With a typical 802.11n wireless connection, you may be lucky enough to get a transfer speed of 80 Mb/s (in other words, 10 MB/s).
If you have 100GB of music, for example, this will take around three hours. Double that time for many people’s real-world wireless performance.
If you’re connected by gigabit ethernet, the same transfer should take around 20 minutes.
Copying your iTunes library with an external hard drive
To copy your iTunes library with an external hard drive, simply locate your iTunes folder as demonstrated as above. Then copy and paste it onto your hard drive. From here you will need to copy and paste the library on the hard drive in the relevant iTunes folder on your Windows or Mac computer.
Importing a new library
Finally you will need to import the copied library to iTunes on your new computer. This can be done by opening iTunes > File > Add to Library...and then selecting the new file you have just copied your iTunes library to.