Kerry's got the right idea. Chances are the new player has a CD with it that you would use to rip songs from CDs and import them directly to the MP3 player. I would imagine that this new software has an "import files" feature somewhere that will import all your existing music files (presumably on your main computer), at which point you can add them to your player (I imagine that this is a portable player, like and Ipod or similar).
I have two portable MP3 players- a SanDisk SDMX1 512R (long out of production) and a video Ipod. The SanDisk came with MusicMatch Jukebox as its software, which would rip the files to the hard drive, where I could rename them and tag them so that the screen of the MP3 player would show the song title and artist info. I recently updated to Yahoo! Music Jukebox (which takes over from MusicMatch, apparently), and when I updated it automatically loaded in all my existing MP3 files.
Itunes for the Ipod did the same thing the first time I fired it up. I continue to use the Yahoo! player simply because it makes files that are compatible with the SanDisk and most other players (should I replace the SD, which I use for running and exercising, it being a smaller flash card based player). I also like the fact that Yahoo! places the new files in a folder in the "My Music" section of my documents. "My Music" is full of file folders with artists names, inside of which are more folders with album names. To me this is just an easy system to back up and find stuff in when I want to use files on a different machine. I ripped a couple of CDs with Itunes and have yet to figure out where the heck it put the files. They play, and I still have the discs, so I'm not bothered.
-William
(PS, just to add to the wierdness, my birthday is next week)