Getting It All to Work
You'll find a huge number of audio and video formats floating around, and no player can handle them all. That said, .mp3 audio support is universal, and support for unprotected iTunes music (.m4a files using the AAC codec) and unprotected .wma music is common, too. Video is trickier. Many devices support Xvid video, for instance, but some require the accompanying audio to be in .mp3 format, while other players may support Xvid video using AAC audio as well. If you have a preference, consult our features comparison chart for detailed info on video-, audio-, and photo-file format compatibility.
The Apple TV handles compatibility problems in a simple and convenient, but limiting way. It uses iTunes, on either a Mac or a PC, as a proprietary media server (software that organizes content and sends it to your streaming device). If iTunes can play the file, so can the Apple player. If iTunes can't do it, neither can Apple TV.
Every other product (except the Mvix) comes with software--usually Universal Plug and Play (UPnP) media servers that organize media, send it to the streaming device, and control what folders get presented to it. Nevertheless, you don't have to use this software, since the devices can see shared folders on a network and play files from them. But if you use this method of accessing your media, the streaming device's on-screen menu will probably just show you files in folders, whereas music and video accessed through a server will be organized by genre, performer, and so on.
Windows Media Connect (WMC), Microsoft's UPnP server, is built into Windows Media Player 11; it's a download for XP users, but standard in Vista. WMC adds a very nice feature: It allows some players, including the Buffalo Technology, D-Link, and Netgear models reviewed here, to play protected .wma files bought from services like Napster and MSN.