This will play any .wav you wish. To add, just hit "A"/"+"/the space bar.
If you type in "songtrack #" then it will select "songtrack 1" through "songtrack 99".
A nonexistant .wav will simply be passed by on its turn to play, making the "#" feature all the better.
However, one unfortunate feature is that the existing program automatically selects files from C:\Documents and Settings\Username\Desktop\Songs. As a result, the first time you run the program, it will ask you for your username as it appears in the ...and Settings\Username\Desktop... folder. Double, triple, quadrouple check this.