Try one of the Descent compatibility projects!
Both of the following allow you to run your installed Descent and/or Descent II games with 3D acceleration, sound updates, built-in online play functionality:
DxX-Rebirth: For Descent & Descent II
This one is the choice for those who want the "classic" gameplay. Simple, straightforward.
D2X-XL: For Descent & Descent II
This one is the choice for those who want all the new "bells and whistles". Lots and lots of gameplay features and graphics options.
(Personally, I use both. )
Enjoy!