First, get a laptop computer. Since a laptop is becoming essential for so many other things in life, this doesn't necessarily mean you have to make a special investment, and the laptop you use for email and other stuff can do this job just as well. Just be sure you have enough hard drive space for the music.

I would advise against using an iPod or other MP3 Player for this purpose. While it is wonderfully portable, and might do the job if you have only a few tracks to search, if you are a crazy man like me, and have thousands of tunes, many with the same name, on your iPod, finding the right selection by spinning a click wheel can be even more time consuming and annoying than shuffling CDs. With a laptop, you can organize your stuff just how you need it, and search it with a keyboard.

Further, you can't vary the tempo on an iPod, but you can on a laptop.

Second, get a speaker system. The size and complexity of the speakers depends entirely on the size of the space you are filling. Some of the plug-and-play speakers currently available for computers have, at a very reasonable price, enough pizzaz to handle a moderate size rehearsal hall or church social room.

However, if you have a large space to fill, you may need to invest in something a little more formidable. My solution was to go to the Guitar Center or any other place that caters to the needs of musicians and DJs, explain the situation to them, and get their suggestions for the speaker that combines sufficient power, portability and simplicity. This could end up costing a few hundred dollars (perhaps $400 or so). You probably don't need to get a full DJ set up, with mixing board and such, if you get a speaker that can stand alone. Unless you are keen to become a DJ and have multiple speakers and a mixing board, make it clear to the sales staff that you need a speaker that can run without a mixing board.

If the place where you do your thing has an existing sound system, or you have one that works fine for you but you haven't plugged a computer into it, you need to invest in a fairly inexpensive cable. This has a 1/8" pin on one end that plugs into the headphone/speaker jack in your computer, and the other end is a two pronged RCA stereo plug (one red pin, one white pin). This is a standard input on nearly every sound system built in the last 20 years.

The cable is available almost everywhere. Here is one from Guitar Center which goes for $29.99.

And now the third point: most dance teachers like to vary the tempo on their selections. This feature is often the reason they cling to old tape players, CD players or Karaoke machines that have this "variable pitch" feature. Again, this is easy to do for a laptop. I use a piece of third party software called "Amazing Slow Downer". This software is available for Windows and Mac, and costs $49.95.

To use it, I just find the piece I need in my iTunes library, drag and drop it into Slow Downer, and then play it as fast or as slow as I need to. A caution though: MP4 files, with Digital Rights Protection, such as you get from the iTunes store, will not play in a third party application like Slow Downer. You will want to be sure that the selections you are using that need variable speed came from a source other than the iTunes store (like a CD).

Finally, you will need to get your dance class music library into your computer. This is easy, but time consuming. While I use iTunes, Windows Media Player will work just as well. If you have only a few hundred pieces to keep organized, this should be a piece of cake. If you have thousands, storage space on your hard drive may become an issue and you may want to invest in a remote hard drive that connects by USB or Firewire to your laptop.

And finally, be sure to back up all your music files to a remote hard drive that is not the one you take on the road with you. All computer hard drives, and all remote hard drives will fail eventually. Digital music collections can represent a major and very fragile investment, and the more places you have copies of your files, the better off you are. CDs are also not a reliable back up. They are subject to loss, physical damage and, over time, they will just spontaneously die. Most commercial CDs will last you a few decades. The CDs and DVDs you burn on your computer, a few years.

That pretty much sums it up. So, you dance teachers, there is no longer any excuse for time wasted at classes while you cue tapes or shuffle through CDs and paper playlists, mumbling and cursing, while your students, poised to begin, fidget uncomfortably -- and if you do it right, you will never again have the "Oh damn, I left that CD at home" moment. It's the 21st Century gall darn it! Get with the program!