Who can resist a good Zune vs. iPod prizefight? In fact, these days it's downright necessary, considering that the iPod Nano and the flash Zune look like they've been separated at birth. The truth is that most of the similarities between these two MP3 players are only skin-deep. The Zune's Wi-Fi downloads, FM radio, and Zune Pass subscription support are very different from the Nano's Genius playlists, iTunes movie rentals, and shake-to-shuffle novelty. But when it comes right down to it, which one is better? Which pocket-sized MP3 player is worth your hard-earned cash?