No clue. Check out gamespy or the All Seeing Eye and look for servers with lots of people in them. I've found a couple of servers that can host 20 people without crashing. They are rare gems indeed, but they exist.
Well erm... ah... try the ... options? Hah, I don't use it, I just tell other people too. I'm sure it can be set up to locate those servers, but I'm not the expert to tell you how. I tell people to use the All Seeing Eye because I have a thing against good programs who sell out, like gamespy.