I have a discontinued dell pocket dj player that

Go to dell.com and enter the DJ's service tag ID on the back of your player on the support section. It will give you a list of drivers and software that you will need for your DJ. If you are running Vista, download the XP drivers. They will work fine.

You have to make a choice.
With Vista, I'm not sure, but you may have no choice.
What I mean is, with XP, if you load the 'Plays for sure' version of the driver (the latest one listed) then you will HAVE to use Windows media player to load music on your DJ. Playlists are a problem and the organization of the music is poor compared with what you get using Dell's Musicmatch (version 10 seems to work best all around) Musicmatch and Dell DJ Explorer will NOT recognize your dj, unless you don't have WMP installed, and then it might not recognize it anyway. I've seen both results on different computers.
I don't use Vista so am going by what reports I have had about it. With Vista, there is no choice. Vista won't recognize your dj unless you use the latest 'Playsforsure' version of the drivers, and then you are stuck with Windows Media Player. If you change back to the earlier non-Playsforsure version, Windows Media Player won't recognize it but neither will anything else (that's usable) Wish I had a better answer.

Since you have Vista, you'll especially want to download the firmware, which starts with a 2. To do this, though, you'll have to try to do this on a computer that runs on XP. Also, be sure to back up all of your music, first. Downloading the firmware basically reformats the device. Since I've downloaded the firmware, my Vista computer recognizes it. The problem for me, now, is driver and DJ explorer don't seem to work with the device. I can load music onto it via media player, but because of the driver issue, I can't create playlists on it. Anyone know what to do from here?