I am teaching an introductory college level class about Unix (with bash shell. The equipment I have available is standard PCs in dual-boot mode, meaning they can boot in either Linux or Windows XP. When they come up in Linux mode, the PCs are not connected to a central server.
I would like to impress my students with the multi-user capabilities of Unix (Linux). How can I run multiple users on a single PC? Thank you.

You mean not connected to a LAN at all?

Or not part of a Windows domain?

Or what?

At my work we have several shared Windows machines that are used by one person at a time from their own Windows or Linux workstation using some form of either VNC or Remote Desktop (we use a few different forms). It is inconvenient, because before grabbing a system with VNC or Remote Desktop you can, at most, tell whether someone else is logged in. You can't tell whether they are actually doing something or even if they are still connected (vs. just forgot to log out when they disconnected).

We also use several Linux systems via various forms of putty, ssh, X windows servers, or VNC. Since Linux is inherently multi user, there is no conflict except for CPU time and ram, which you can check with top before launching a big job.

So depending on how you have things networked, and on what other Linux or Windows workstations you have handy when you want to demonstrate "multi user", you might want to use one of those methods to remotely log into a Linux system while someone else uses it directly. All of X windows, VNC, ssh, and maybe putty are easier to install and use on a Linux workstation to access another Linux system on your LAN than to install on Windows for use in accessing Linux. But all of them can be installed on Windows for Linux access. Most people here use Windows workstations to access the Linux systems.

Students may not understand the value of using one computer as a terminal to use another computer. So any impressiveness of Linux multi user may be diluted by the need for each user to tie up a full computer to get access.

A multi seat single Linux system would get the point across in a more impressive way. But it is much harder to set up. You obviously need a second of each of monitor, keyboard and mouse. I don't know how much harder it is with one dual head display interface. I think using a second display interface instead of one dual head is generally recommend. Even then the software setup for dual use can be tricky. Also IIUC, if you have both keyboards or both mice USB (vs. one PS2 and one USB), the identity of the keyboards or mice tends to get swapped on reboot.

I'm hoping soon to install SGE (Sun Grid Engine) to distribute work across several Linux systems (rather than have individuals use top to find out which systems are lightly loaded enough for the task they want to run). That might make a more impressive demonstration for you than either remote log in or multi seat. But I think you would need to first switch all the Linux systems to some form of shared authentication of users (we already have that here). Once you have properly configured SGE, I think you could demonstrate tasks submitted to SGE automatically running (as the original submitting user) on whichever of the Linux systems is lightly loaded, even if that Linux system has someone else logged in (assuming they aren't using a lot of CPU time).

mvernia,

vnc can be quite impressive. Boot one of the machines into Linux and create accounts for some of your users.
Start vncserver sessions for each user with different desktops, say KDE, GNOME, ... whatever you like. The idea is to be able to tell them apart.

On the other systems (Windows or Linux) run vncviewer and connect to the vnc server system.
Its unlikely you have VNC installed but its OSS.

Its a very visual demo of multi-user.

Each user can use their own session.
Now have them close the VNC viewer applications and swap seats, then reconnect. They will find their sessions just as they left them.