Say I want to play some RTCW for nostalgia..

Used to play RTCW on Xbox Live on and off from like 2003 to 2006, watched some WarwitchTV and got the nostalgia going on..

If I want to play some RTCW, and I do mean RTCW not Enemy Territory or any of that non-sense. Can I just get it on and Steam and voila or will I need some add-ons or whatnot? And there people still playing? I remember like a year back I dl'd a copy and all of the servers running were bots..