If you want to restrict access to the network identification page:

Hive: HKEY_CURRENT_USER
Key: Software\Microsoft\CurrentVersion\Policies\Network
Name: NoNetSetupIDPage
Type: REG_DWORD
Value: 1

Control Panel Network Policies Registry Tips:

Disable Network Controls
Disable File Sharing Controls
Disable Print Sharing Controls
Hide Identification page
Hide Access Controls

Gives an in-depth look at the NT/Windows 95/98 system policies. Step-by-step walkthroughs.