Before I dig too far into this question, I want to highlight that a lot of third-party Mp3 players are designed to work with existing software and drivers, actually, not require their own. Perhaps you're supposed to use Windows Media Player, for example, to manage the music on your player with it being viewed as simply another device.

Further, reading the forums online suggests that a lot of people who have Windows and an off-brand mp3 player (here I'm using "off-brand" to mean anything that's not an iPod. :-) find that installing some of the available digital camera drivers for Windows does a good job of having their devices suddenly appear.

Let's look at your specific device, however. I'll start by going to Google, not the Sony site, however. Just Google download sony mp3 driver windows and you'll find over two million (!) matches, notably including a link to a Sony camera and mp3 player driver at OpenDrivers.com: sony driver from OpenDrivers.com.

Of course, adding site:sony.com to the Google search also quickly reveals that they have some apps you can download too, all from esupport.sony.com.

Since I don't actually own a Sony mp3 player, I can't pull out a typical model number, but I bet that you can dig up a model number from your own player and add that to the search. A likely place to look: underneath or behind the battery. Armed with that, I would also go to the Sony site itself -- as listed above -- and see what they list, because that way you can get all the supplemental applications and utilities too.

Hope that helps and please do come back and report on your results getting your Sony player to work with your PC!