Still play this on DOSbox fairly often. Actually still play a lot of old DOS games - lots of good old game memories: Doom and all it's variants (of course), Tyrian 2000, Descent, Beneath A Steel Sky, Dungeon Master, Captain Comic, Commander Keen, Duke Nukem (before the 3D) - lots of great games came out on PC-DOS.
Got any
Heretic or
Hexen in the mix?

Those are some classics. Super pissed that my dad threw away my copy of the former, though... Probably looked at the title and said, "That's unChristian!" and chucked it. That was a long time ago...
I suspect he threw it away, anyway. Game just disappeared one day. So did my copy of
Space Quest 6, roughly around the same time. Apparently jokes about jock straps were too crude for a 12-year-old... (I remember him complaining about that particular issue, and he must have had a fit when my friends and I all gathered round the computer to play and laugh about the game.)
And maaaaan,
Descent... If any DOS FPS ever needed a re-release on a modern console, that is it. XBLA's good for old FPSs.
DOOM I and II,
Duke 3D,
Wolfenstein...
Well, no,
Quake deserves a console re-release more than anything 'cos it's pretty much the greatest FPS ever, but
Descent is close—and it gets bonus points for being, to my knowledge and experience, the first fully 3D, polygonal FPS ever made—and they really capitalized on that by letting you go IN ALL DIRECTIONS! Crazy game.
Descent II is no slouch either, but
Descent 3... Eh.