iTunes'Autosync feature makes keeping your iPod up-to-date a total breeze, but there's a big catch: You can sync your iPod with only one computer. Lots of people have music scattered around multiple machines: a couple of different family Macs, an office PC and a home PC, and so on. If you want to load up your music from each of these sources, you have to change your iPod settings to manual management. That's easy to do. Just connect your iPod, select it in the Source list, and then click the Summary tab in the iTunes window. Then:
Scroll down to the Options area and turn on the checkbox next to "Manually manage music and videos". Click the Apply button in the bottom-right corner of iTunes to make the change.
Don't forget to manually eject your iPod from iTunes every time you want to remove it from your computer. (Manual update gives you total control, but as Uncle Ben said in Spider-Man, "With great power comes great responsibility.") Eject the iPod by either clicking the Eject button next to the iPod's name in the iTunes Source list or by pressing Ctrl+E (⌘-E) to properly free the player from the computer.
Your iPod's Summary screen (in iTunes) shows whether your iPod is formatted for Windows or Mac. If you have a new Classic or Nano and want to use it with both a PC and a Mac, connect it to the PC first and have iTunes format the iPod for Windows. A Mac can read the Windows format just fine, but Windows won't recognize the Mac format without special software. The iPod Touch will talk to either computer, no matter which one you use it with first.
Learn more about this topic from iPod: The Missing Manual, 8th Edition.
Get the scoop on iTunes 9 and all of the newest iPods with this bestselling Missing Manual. Apple's gotten the world hooked on portable music, pictures, and videos with its amazing entertainment center, but one thing they haven't delivered is an easy guide for getting the most from it. iPod: The Missing Manual gives you a no-nonsense view of the latest iPod line, with crystal-clear explanations, easy-to-follow color graphics, and expert guidance on the most useful things your iPod can do.