By request of Shaknunic, our resident Vista proponent and fellow ASRock 970 motherboard user, I've decided to add his TS3 server, which works with any version from 3.0.18.2 to 3.1.10.
Shu recommends using 3.0.19.4 (the last XP-compatible version), but Vista/7 users can also use 3.1.x versions (3.1.5 for Vista, 3.1.10 for 7 respectively) as well. This server will allow us to do voice chat from our old machines.

Got an even older machine running 98/Me, 2000, or XP SP1 or SP2?
Shu's got you covered as well with a TS2 server.
Do note that you have to register in the TS3 server in order to be able to join the TS2 server, in case.
TS2 users will have a special badge of sorts in the TS3 server.

Happy fragging!
~Tsubo-D~