The original Squeezebox was one of the very first Wi-Fi music players, and Slim Devices has kept it in the technological lead with version 3 of the hardware. One of the Squeezebox's major strengths is the open-source SlimServer software, which runs on your Windows, Mac or Linux PC, and supports streaming of iTunes audio (although not "protected" Music Store files), WMA, Internet Radio, the Rhapsody service, and the proprietary SqueezeNetwork, in addition to almost every MP3 encoding format known to man, including lossless. The SlimServer can even stream your music library over the Internet to a software player like iTunes or Winamp on a remote computer, so you can listen at work or on the road as well as at home. And it supports multiple Squeezeboxes, so you can play different music in different rooms simultaneously.

The hardware is equally adept, with digital optical and coax outputs as well as standard RCA jacks, a headphone jack, and an Ethernet port that lets you use the Squeezebox as a Wi-Fi bridge for an Ethernet device like a printer or network drive. Through the SqueezeNetwork, you can even listen to Internet Radio even if your PC music server is offline! The large fluorescent display is readable from across the room, and an infrared remote control is included. Be sure to order the wireless version ($299), since a wired-only version ($249) is also available. Comes in both black- and white-edged casing.

The Roku SoundBridge Radio ($400) combines many of the best Squeezebox features with a standard clock radio -- you can tune into regular AM/FM radio, in addition to digital music, and wake up to either. You can also tune into Internet Radio while your PC music server is off, and it supports a variety of servers, including Windows Media Connect, iTunes, MusicMatch, Rhapsody, and even the same SlimServer software that comes with the Squeezebox, so you can choose the software that's best for your library. When using Windows Media Connect, you can play protected Windows DRM files purchased from any PlaysForSure music service, such as Napster, Urge and MSN Music (these files aren't supported by SlimServer). Yahoo Music Unlimited is also supported but not protected iTunes Music Store files. Another nice feature is that it has a memory card slot so you can play music stored locally, rather than on a networked computer.

The key drawbacks to the SoundBridge Radio are that it does not have audio outputs other than a headphone jack, nor an Ethernet port or remote control. It is designed as a standalone unit, and has built-in speakers. Roku also sells the SoundBridge M1001 ($200) without the AM/FM clock radio and speakers, which has the additional ports and remote. Since you can have multiple SoundBridges connected to one server, you could have a Radio version in the bedroom, and an M1001 in your living room.

Aside from Apple TV, the AirPort Express is the only wireless music streamer authorized by Apple to play the protected AAC files you buy from the iTunes Store. It has a digital optical output for connecting to your stereo system, or you can use an adapter for standard RCA cables. But perhaps most importantly, the AirPort Express doubles as a standard Wi-Fi router, with full software support for both Windows and Mac. The compact palm-sized unit also makes a great travel router, for unwiring hotel or conference rooms on the go. The downside compared to the Squeezebox or SoundBridge is the lack of a display or remote control. You'll need to control playback directly from your PC or Mac, or buy a third-party remote control like the Keyspan Express Remote. You also can't have multiple units playing different things in different rooms without additional PCs or Macs running iTunes software. Also, as these are routers, you'd need to configure multiple units appropriately to not conflict with one another. But the AirPort Express is only about $120, less than half the cost of the SoundBridge Radio or Squeezebox.

The Linksys Music Bridge is the cheapest wireless music streamer of all, at around $80. It is also the only unit besides the AirPort Express that lets you listen to protected iTunes Music Store files and indeed protected music from any source. It's able to do this trick because it takes a different approach to playback. Instead of decoding files at the player end, software you install on your PC simply takes the sound output from your computer and sends it to the Bridge -- alert sounds and all! The Bridge is then connected to your home stereo. You can use any music software you like: iTunes, MusicMatch, WinAmp, or whatever. As with the AirPort Express, the Linksys has no remote control or visual display, you need to control playback from your computer, and it's not a multi-room solution. But it's a very neat poor man's streamer that bypasses copy-protection hassles. If you have a wireless laptop, this is a cleaner solution than running wires from your computer to your home stereo.

At a minimum cost of about $750 for one controller and one player box, the modular Sonos Music System is a high-end solution in a class of its own. There are three basic components that you can combine in up to 32 rooms -- each playing its own tunes. The wireless handheld controller has a large color LCD and scroll wheel for easy navigation of large music collections, something that can be a real hassle on the small remotes that come with the Squeezebox and SoundBridge. You can wander from room to room with the controller, no need to buy one for every room (its $399). You do need a player unit for each room you want to stream music to, however. There are two options: the ZonePlayer 80 ($349), a decoder box that connects to your stereo or amplified speakers, and the ZonePlayer 100 ($499), which includes an amplifier as well so all you need is a pair of regular speakers. The two-room Music System ZP100 bundle for $1199 includes two ZP100s and one controller. The Sonos system supports Windows DRM files used by PlaysForSure stores like Napster, Yahoo, Urge, AOL, Wal-Mart and Zune, as well as the Rhapsody and Pandora subscription services.