It's easy to transfer songs from an iTunes program to an iPod--just plug the iPod into the PC. Transferring songs from the iPod to another PC might not seem as simple. You have to transfer the songs manually, as the iPod won't do it automatically. This simply requires you to locate the files on the iPod's hard drive; since the files are normally "hidden," you must take steps to reveal them.

Transferring Files

Your PC needs to have iTunes installed on it so it will work with your iPod. If your Windows PC doesn't have iTunes, you can download and install it at no charge from Apple's website. Once you have iTunes installed, connect the iPod to your PC using USB the cable that comes with the iPod. This should immediately cause the iTunes program to open and "sync" with the iPod; to stop the syncing, click on the X in the upper right corner of the iTunes window. On your Windows XP PC, go to the Tools menu in Windows Explorer and select "Options," then check the "Show hidden files and folders" box in the View Tab, and click "Apply." Click the icon for your iPod in Windows Explorer. By drilling down through iPodControl > Music you can access the songs on your iPod. Once you find the iPod's Music folders, drag them into the PC's iTunes program or another hard drive folder.

Authorization

You will need to authorize the PC to play any songs that you purchased from iTunes on a different computer. To authorize it, select one of the songs you transferred from the iPod and click on the iTunes "Play" button. This brings up a dialog box asking for authorization. In the appropriate text boxes, enter your Apple ID and password. Apple allows the songs on one Tunes account to be shared on five different computers. If you have authorized the maximum number, you can de-authorize another PC to free up a space for the new one. Open iTunes in the other computer and go to Store--Deauthorize Computer (go to the Advanced menu on earlier versions of iTunes). In the next box, select "Deauthorize Computer for Apple Account," using your Apple ID for verification.

Source:

www.makeuseof.com: Move Music from iPod to PC in 5 Easy Steps

Apple.com: Support