3 users

[techieMoe]

Nah, if one of those users had the name "1337_h8x0r777" then you'd have something to worry about.

[scientica]

The explanation for the 3 users could be as simple as this (note there can be many more, and most are also 'harmless'):
during system start up a number of services/servers are started up, some run as root some as other users eg, apache2 might run as a user named "apache" or "http", some 'croned' job (read: scheduled job) might run as another unprivileged user (for security reasons - one should avoid beeing root user when possible, as the system stabillity is in 99.9% of anything really bad that can happen only can happen when the root user is doing it (what the root user can't do in linux _no one can_ -- yes root can delete all files while the system is running, and don't try it, all that happens is after the rm command is done is that you'll only get 'command not found' when trying to do anything)).

[gwalters]

Most times when i use my puter it has zero users. I startx& in a console then exit. X runs but no-one is logged on. :P

[madninja]

You can use the last command to see the last logins to your box.
This will tell you what users have been logging in and from where
ie pts/1[IP]

[wavz]

Learn something new everyday

[cockraml]

On my machine, I have a user in who for every console that I have opened in X.

[wassy121]

Yes, every login shell (console, xterm, screen) by default writes the user login information into wtmp. You can see who has logged in recently with 'last'.

Best,

Samuel