Ubuntu Linux is a popular alternative for users frustrated with mainstream operating systems. Its Unity interface is polished and easy to use, borrowing design cues from both Windows and Apple's OS X, and incorporating bright ideas from its own designers as well. Unity has largely eliminated the ease-of-use issues that dogged novice Linux users for years, but the problem of replacing your familiar software applications remains. Many mainstream programs such as iTunes aren't available for Linux, so you can't simply download a Linux version. Instead, you'll need to find a workaround.
No Wine for You
The first option for running Windows software on an Ubuntu computer is Wine, a Windows compatibility program. It's in the Ubuntu Software Center and can be installed with just a few clicks. Its developers maintain a database of common programs (see Resources), rated by their likelihood of running successfully. Unfortunately, iTunes is notoriously reluctant to work with WINE. Some versions work partially, but on the whole, it's an exercise in frustration.
The best option for working with music on your mobile device is to settle on one of the native Linux-based music players. There are several, with varying features and interfaces. They're all free and many are available directly from the Ubuntu Software Center, making it easy to try several and settle on one you like. Rhythmbox, Banshee and Amarok are the most popular, and Clementine and Guayadeque are also widely used. None can read your iPhone or iPod's playlists directly, but you can transfer songs to and from your device seamlessly. Banshee can also transfer playlists to your device.