For those who manage Windows XP or Windows Vista computers in a school computer lab, internet cafe or library, Microsoft provides a tool called Windows SteadyState. If you want to know more about Windows SteadyState then I recommend reading the Windows SteadyState Handbook or FAQ.
But hey, who cares about Windows XP or Vista nowadays? What about Windows 7? Well unfortunately Windows SteadyState doesn’t support Windows 7 and it appears that Microsoft has no plans to provide a newer Version that does support Windows 7. But Microsoft did recently publish some guidance on how to get a Steady State for Windows 7.
Group Policy Settings for Creating a Steady State (This document might also be of interest if you’re just looking for client lock-down ideas)