Need Little IT advice here...

[Bruno Wolff III]

On Thu, Aug 11, 2011 at 22:57:18 -0500,
  Manuel Escudero <Jmlevick at gmail.com> wrote:
> 
> I want to set a standard configuration in a machine and then
> let that machine to be used by many users, but as soon as
> the user Log Out (preferably in that moment)
> I want the machine to undo all the possible
> changes the user may have done while he/she was using it.

xguest might do what you want.
Description :
Installing this package sets up the xguest user to be used as a temporary
account to switch to or as a kiosk user account. The account is disabled unless
SELinux is in enforcing mode. The user is only allowed to log in via gdm.
The home and temporary directories of the user will be polyinstantiated and
mounted on tmpfs.