Probably not essential to most people, but when you’re sharing your Macbook or like me expect to be using it only for a while, it is useful to create a second user. That second user will have all the same applications available, but will have its own settings, user-names etc.
Because I didn’t do that right away, I had to redo some of the settings that I did for the first account. But now it is less a problem when I have to hand in the Macbook again. Without my password they can’t log-in using my user and my settings and stored user-names etc. are safe.
To create a new account goto System Preferences > Accounts
You’ll probably first have to unlock the Accounts screen by clicking on the lock in the lower left corner.
After that click on the + about the lock to add a new user.
I gave my user administrator rights so that I could still do everything that I wanted.
If you’re going to share your folders with XP users, you also need an user account which determines the username and password that XP users need to answer to get access. It is best to not use an administrator account for that purpose.
Just like XP you have a number of options for user accounts. You can for example determine which account is used to automatically log-on when the Macbook is started. The account names can be displayed next to the clock in the upper right corner of the screen enabling easy switching between users while staying logged in.