Simplicity personified, 1by1's interface is the familiar Explorer-type window with a directory tree and viewing pane. The background color is blue, and there's a toolbar with small icons that let you play, pause, search, etc.--but otherwise it's that with which all Windows users should be familiar. Basically, you browse to the folder with the tunes you want to play, press play, and 1by1 will render all the tunes in the folder/directory (hence its secondary "The Directory Player" title). It's great for people who have a well-organized collection and like to play entire albums.
1by1 lacks the library functions for sorting by artist, album, etc. that makes programs like iTunes so appealing to many users who don't know how to organize files on disk. There are, however, playlist functions so you can play tunes from multiple directories. Surprisingly for program so lightweight, there's also a three-band EQ with adjustable center frequencies as well as an audio enhancer (think WMP's SRS WOW) on hand.
As installed, the player handles only MP3 files using Windows XP/Vista's built-in codec, or the mpglib.dll if present. But you can grab free Winamp plugins to add support for WMA, OGG, FLAC etc. 1by1 is ideal for super light Windows installations like you'll find on netbooks, or for the minimalists amongst us. It's a great little, and I mean little, program.
--Jon L. Jacobi