everytime you open a new terminal it should count as a new user. For example on my FreeBSD box here (my main machine until i get a new mac) my uptime looks like:
10:32AM up 33 days, 17:49, 4 users, load averages: 0.12, 0.09, 0.06
It shows 4 users, however, I am the only one using it. But, I have 3 xterm windows open, each one taking up login space. The load averages go like this:
The first number is the load for the past 5 minutes, the next number is the load for the past 10 mins, and the last number is the load over the last 15 mins. These numbers are NOT a percentage of the maximum amount of load possible, i.e, you can go over 1.00 for a load average. In fact I have had this machine with load averages around 17.5 and it gets VERY slow to work on.
Just thought I should clear some of those things up.