There are numerous contenders, though only a handful have acquired critical mass. All are free for downloading from the Web, but some require a payment of around $30 if you want to add important capabilities.

I've been testing three of the most popular virtual jukeboxes for Windows PCs, and have been surprised at the results. The best program isn't Nullsoft's Winamp, which popularized the category and was recently acquired by America Online. Nor is it the most heavily hyped program, RealJukebox, from RealNetworks. Instead, I strongly preferred a less well-known contender, MusicMatch Jukebox, from little MusicMatch Inc., of San Diego.

Jukebox programs should do more than just play back music. They shouldcollect and organize the songs on your PC into a master database, or library. Then they should allow you to create and save playlists, which tell the jukeboxes which songs to play, and in which order. They should also be able to convert tracks on CDs you own into MP3 songs on your hard disk, a process called recording, or "ripping."

Finally, the programs should manage and display the rich non-musical information contained in every MP3 file. These so-called tags can include the song's title, artist and album, its genre, copyright date, lyrics, notes on the song, and a picture of the artist or album cover. This information is a great boon to music collectors and a core advantage of the MP3 music format.

MusicMatch jukebox, version 4.1, can do all of these things, and does them better than the other jukeboxes I tested. It is both the most powerful jukebox program and the easiest to use.

MusicMatch includes several modules, which can be displayed alone or in various combinations. The music player, whichuses the traditional controls found on a CD player, is the heart of the package. At its side is the playlist.

As in the other jukebox players, this player module can be shrunk to a very small size so it doesn't get in the way. And you can change the look and feel of the whole program by switching among various themes, or "skins," which alter the basic color and style of the software.

Other MusicMatch Jukebox windows include the music library, which contains all of your songs, whether or not they are included on the current playlist. You can play these songs individually, sort the library by various categories and add new songs to it with ease. There's also a graphic equalizer, to change the way songs sound, a recorder for converting CD tracks to MP3s and a mini Web browser for downloading music.

But where MusicMatch Jukebox really shines is in its handling of MP3 tag data.

It offers numerous ways to annotate songs. And it's the only one of these programs that lets you display the lyrics of a song, orother info, along with a related photo -- usually of the artist or album cover -- while it's playing. It doesn't automatically provide the lyrics or photos; you have to add them manually or find them on the Web. But it handles them beautifully.

MusicMatch Jukebox is free, but it takes $30 to upgrade to a version that will record CD tracks at the best sound quality. My only gripe about the program is that it is very demanding of the PC, and playback can slow down if the computer is busy doing too many other tasks.

WINAMP IS a competent player, but it pays almost no attention to tag information and can't display lyrics or photos. Instead, the program seems built around ancillary visual effects -- displaying a sort of oscilloscope while the music plays. But the controls are hard to figure out, and the song titles and other text are hard to read. Also, Winamp lacks a recording function for CDs.

When RealJukebox came out a few months back, some in the media hailed it as if it were a pioneer in the categoryinstead of a latecomer. It has ridden a wave of hype ever since.

It has one nice feature -- it can download songs directly to handheld music players, like the RioPort Rio or Creative Nomad. Otherwise, I found its approach to be geeky and computerish. Instead of presenting your songs and playlists as libraries or databases, RealJukebox uses an interface reminiscent of a Windows file listing. It is hard to use and understand, in my view. RealJukebox also barely uses or understands tag information. The basic, free edition does nothing with tags, and even the $30 Plus version, which you need to record full-CD quality, has a very limited tag-editing capability, and no ability to display lyrics or photos.

Also, RealJukebox is aggressive and intrusive. On my PC, it kept trying to grab control of CD playback, even though I preferred a different program for playing CDs. It placed its icons all over my windows toolbar, and after I used one of its features, it inserted a plug for itself in all my song tags.

Allthese programs are changing and improving, and more are on the way from Microsoft and other companies. For now, if you want to get the most out of your MP3 collection, I recommend MusicMatch Jukebox.

(www.ptech.wsj.com)