One way to solve this problem is to have them go to the control panel, and add a password to the username.
this way when windows boots it will show their username and ask for a password.
After this, to add a user that is not an administrator go to control panel and add a user making sure that it is not an administrator. Add a password and then when the machine boots, it will have 2 usernames.
Selecting the added user without admin priv's will then ask for password and setup the new users desktop and user files.
I would recommend that anti-virus and other general programs be installed under the first administrator userid and make sure that the programs installed are allowed for all users of the computer.
Is this the kind of info that you wanted?
One thing to remember is to never delete the original adminstrator priv's userid or you will be screwed.