The FUS works pretty well.
I haven't used it much but it is a nice touch. On 10.3.7:
Apple -> System Preferences -> Accounts ->
Click on the Login Options thing in the list on the left side.
Check the "Enable fast user switching" box.
To add more accounts, click on the "+" box below the Login Options thing.
When everything is ready, you'll see the Username at the top right of the bar at the top of the screen. Click on it to change to log in as a different user. You'll see the desktop rotate 90 degrees when you're successful. It's pretty neat.
Luck!
Cheers,
Scott.
