One of my favorite DOS games, Mechwarrior 2 combines superb gameplay with an amazing soundtrack and soundeffects.
You can find the OST on Youtube or download it here.
This is one of my favorite soundtracks of all time, every track has an amazing atmoshpehere and quality..there's really no game that can compare.
The feeling of booting up your mech on an alien planet with all the machine sounds buzzing to life, the eerie first seconds of music in the background, the computer voice noting the ambient temperature..the level of immersion created is just perfect.
It's definitely worth checking out the full soundtrack besides the favorite tracks I listed here. Or even better, boot it up on DosBox.