Go to www.handago.com and search by the program name. That will get you there.
Or click on the Pocket PC button at the upper left. Take a look at the software list. If you scroll down, the software is sorted. Look under Entertainment->Music.
I've played around with both PocketMusic and WithMP3
Guess I like WithMP3's sound better but I find the playlist interface far superior in PocketMusic : You can order the songs by track#, file name ... This is not possible in WithMP3 (except if you want to do it manually obvisouly !)