Open iTunes > Help > iTunes Help
In Contents > Expand The iTunes Store > Select Managing Your iTunes Store Account.
You'll see the following topics which should answer your questions.
- Managing your iTunes Store account
- Setting up an iTunes Store account
- Signing in or out of the iTunes Store
- Changing your iTunes Store account information
- Authorizing a computer to play iTunes Store purchases
- Viewing your purchase history
- Making sure you have all your iTunes Store purchases
- Moving your iTunes Store purchases to another computer
- Using iTunes behind an Internet firewall
If you want to move the contents of the ipod onto the PC you'll need to buy a third party program. Use Google to find one on the internet.
Thanks to xpcman for this tip on the forum.