I'm going to try and start a NS and possibly one other game server this summer with my old desktop parts. I was wondering, with a relitively average/standard linux distro, how many players could a server with an Athlon XP 2800 and a gig of ram support with a good (under 80 or so) ping.

Also would this server be limited by the connection if I was using a 2 Mb up/downlink?

a 2mb up and down lnk is great for hosting a ns server or 2. You wont have any problems with that.

and your hardware will be mroe thana dequate for running one server

Most excellent.