Check out the "Where to play" section on my page (listed in my signature). Though the ingame browser is fine.
1.04 (The latest patch) lets you only see 1.04 games. 1.02 lets you see 1.03 games (and vice versa) but I don't think you can join 1.03 games with 1.02 (for obvious reasons).
So get the latest patch, that's your best bet. It's on LucasArt's JK2 page btw.