Another great option is DXX-Rebirth; which also supports all opterating systems and this one still retains Descent 1 and 2 series with it's original look, thanks to this, it runs on numerous VGA cards as well, besides a new-gen ATi or NVIDIA VGA.
As what I have experienced and heard from others, is that DXX-Rebirth is very stable and user friendly, we have implented UDP for stable network performance as well on any OS out there, as a main DXX-Rebirth Beta tester named as Gold Leader, I find this the best Open Source Descent project out there, but hey this is my personal feeling about it, like that of many others
for more go here:
http://www.dxx-rebirth.com
Holder Of The World's Largest Descent / Freespace Collection: