Domain users .. with Local PC admin rights

Hi,
i am using windows 2003 server and winxp for client machine.All clients are part of domain. our clients are using Oracle application which requires the admin rights in local machhine. I have added usersa in adminstrtator group in local machines. But since i have added to admin groups they have the rights to change the LAN properties. I even disabled from GPO it didn’t work. If i don’t add the users in local admin groups then they don’t have the rights to chane the LAN. How can i block the users changing the LAN properties ?