Do not map with JK2 radiant. It is WAY outdated, 1999 I think.
If you are new, I do suggest Radiant 1.4. If you are not new to mapping, get the very latest version, Radiant 1.5. 1.5 is more power-ful, but a lot of new mappers find 1.4 easier to set-up and get going.
Choose what you want. I use 1.5, but I have been mapping for around a year and a half now.
Quake 2 player.
Real life player.