While the rest of the world has settled on the MP3 format for music distribution and playback in solid-state devices, Sony has plumped for its own ATRAC standard (as used by MiniDisc). This works much like MP3 - music is digitally 'ripped' from audio CDs and squashed to a fraction of its original size, with little loss in quality. But there's more to it than that.

The Memory Stick Walkman is about the size of a fat, neon highlighter pen and light enough to hang around your neck, for which a strap is supplied. The tiny buttons are a little fiddly but the jog dial for the play controls works well and the small backlit LCD screen shows you what you're listening to.

Complications arise with the included OpenMG Jukebox software, which is used to compress CD music files on your PC, making them ready to play on the Walkman. It's easy to use, but the ATRAC files it creates can only be transferred to the Walkman itself: you can't email a song to a friend, for example. And because the files are encrypted, they will play only on the same OpenMG program they were created in.

Also, OpenMG prevents files being sent out to your Walkman more than three times. Imagine a library with only three copies of each book and you'll get the idea.

The reason is copyright protection, and if you're happy to recompress your MP3 collection as ATRAC and lock it inside your PC, there's no problem. But for those that like to make compilations for friends, the system is limiting.