Application rules?

Hi,

I would like to enforce rule that can be done using GPO,

1) Blocking the default games that come with windows,

2) I would like to implement system lock down to prevent new application from being installed on the system, for which i believe i would need MD5 value how do i obtain a MD5 value of a remote client from symantec manager.

3) Would the preinstalled programs write anything new on the registry? or would they just need read premission if so please suggest a application and device rule to block new installations.