That depends on how many features you need. Do you want to build your own music library or just listen to random oldies? Most music is available over the Internet either as downloadable files, of which MP3 is the most popular format, or streams — transmissions that you listen to in real time — for which RealAudio is the most popular. MP3s allow you to save the music and replay it as often you like. But MP3 files are very large, requiring either a fast connection or tremendous patience. For music freaks with broadband, or teenagers with nothing to do, MP3 is the way to go. But if you're still puttering along on a 56K modem, it's less frustrating to stick with streams. Just be prepared for blips — annoying interruptions in the music caused by heavy Net traffic.

You may want to consider other forms of Web-based music before choosing a player. Liquid Audio, for instance, plays high-quality sound files, watermarked to help Web police hunt down sonic pirates. But MP3s and streams currently provide the most material. And whichever you choose — the convenience of streaming or the cutting edge of hi-tech hi-fi for your MP3s — the best player lies somewhere in the list below.

MUSICMATCH JUKEBOX
Time Digital's choice. MusicMatch is more than just a player; it aspires to be the only tool you'll ever need for playing, storing, organizing and copying your music. Naturally, it plays MP3s, as well as both RealPlayer and Windows Media streaming formats (many competitors play only one or the other). It also connects to an Internet database where you can find the lyrics and album covers that go with your music. You can create playlists of your favorite tunes and annotate them with notes and comments. Myriad features help you record your own MP3s from your favorite CDs, and best of all, you can do so at the highest recording rate available in a free player — 128 kbps, essentially CD quality. You can also convert your MP3 files to streaming formats or to the .wav format, which allows you to burn them to audio CDs. With its plug-ins (downloadable extras that expand a player's abilities), MusicMatch can connect with portable MP3 players. The only thing that could use some polishing is the clunky-looking interface, which can be difficult to control. For example, MusicMatch's player, radio and recorder features are all separated into different but connected windows. This monopolizes your desktop and gets quite confusing.

MusicMatch is also the best way for Mac users to enjoy MP3s, but the Mac version doesn't sup-port streaming. For that, a Mac user's best bet is to download RealPlayer. (Everyone interested in streaming music ought to check out Kerbango.com, where you can choose from more than 5,000 Internet radio stations.)
Ease of use: B+
Overall features: A

REALJUKEBOX 2
Perhaps the greatest obstacle now facing RealJukebox is its history. Last year it was revealed that an earlier version of the player could secretly collect details about the listening preferences of its users. It would keep track of your musical choices, encode you with an identifying serial number and send the information back to its servers at RealNetworks. When the public learned of this practice, RealNetworks insisted the information was not being stored and quickly issued patches that disabled the feature. They have now abandoned the encoding practice altogether, but suspicion and resentment linger among online music lovers. RealJukebox hopes to win them back, partly with an incredible collection of "skins" — complex, changeable designs for your virtual music player (one features a dancing scarab).

RealJukeBox also offers great "visualizations," trance-inducing, psychedelic patterns that jump around your screen to the beat of the music. Unfortunately, the ads that appear in the player are distracting (none of the other players listed here are burdened with advertising). If you upgrade to the $29.99 version, you can record faster, do file conversions, print CD jewel cases and playlists, and more. If you want to create MP3s, you will find yourself doing so in an unnecessarily secure nontransferable format (which fortunately can be disabled). Still, RealJukebox has many of MusicMatch's best features, but it's a little simpler and therefore a good choice for the novice.
Ease of use: A­
Overall features: A­

WINDOWS MEDIA PLAYER 7
Microsoft has done it again: entered the game late, that is, and worked furiously to catch up. Windows Media's default interface is easy to navigate, but you need Windows 98 or higher to run it, and it won't play older RealAudio streams. It can play MP3 files but won't let you convert tracks from your audio CDs into MP3, as you can with MusicMatch. Instead, it converts those files into its own Windows Media Audio format and will play them back only on the computer that created them. The skins and visualizations are mostly uninspired. Microsoft will soon begin bundling Media Player in future editions of Windows in hopes of overwhelming the competition with its easy availability — you won't have to download it — and usability.
Ease of use: A
Overall features: C+

WINAMP
Once the standard by which all players were judged — and the software application that single-handedly started the MP3 craze — Winamp invented features like skins and visualizations. But the software has failed to keep pace. It supports neither RealAudio nor Windows Media, offering its own Shoutcast format as a poor substitute. It loads MP3s quickly and offers some 300 plug-ins, including one that lets you control Winamp with a TV remote. But many of these plug-ins were created by enthusiasts (your teenage neighbor, perhaps) and some are buggy. In a recent test, one simply failed to operate.
Ease of use: A
Overall features: C