Victory - Chex Quest
Victory plays when you beat the game. It has a nice uplifting sound played on an electric piano with drum and bass accompaniment.
Chex Quest (DOS)
The song is named D_Victor in the WAD file, the original Doom notation.
Chex Quest 2 (DOS)
Although Chex Quest 2 is a mod that uses most of the original media from the original WAD, the Chex Quest 2 PWAD contains a second copy of the D_Victor MUS file, even though it's the same song.