You can instruct Explorer to not display a drive(s) in the My Computer display. When enabled, this policy removes the icons representing the selected disk drives from My Computer, Windows Explorer, and My Network Places and from Common Dialogs. Note that the registry key is Policies\Explorer.

For example, you create partition E: and use it exclusively for NT's pagefile. To prevent a (possibly ignorant) user from browsing to that partition and deleting files that should not be deleted, apply the following Windows NT / Windows 2000 Registry hack :

Hive: HKEY_CURRENT_USER
Key: Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
Name: NoDrives
Type: REG_DWORD
Value: To calculate the value, add together the numbers for the drives you want to hide, using the formula: A=1, B=2, C=4, D=8, E=16, F=32, G=64, and so forth. To hide D: & E:, the value would be 8+16=24.

To use system policies to hide drives:

Q242092.

Only casual users will be blocked using this policy or registry hack. The Find command finds files the hidden drives. The old Filemanager, winfile.exe, is unaffected by this setting. Sadly, the biggest hole for GUI users, most versions of Office are unaffected by this policy. It is a barrier but if your goal is to secure the drives in a student lab environment, there are many ways around or over the barrier.

Desktop and Explorer Restrictions Tips:

Desktop icons hidden
File menu in Explorer is removed
Map Network Drive and Disconnect Network Drive menu from Explorer removed
Network Neighborhood icon removed and prevent network access from Explorer
Common Groups from Start Menu removed
Find command removed from Start Menu
Run command removed from Start Menu
Shut Down button removed from Start Menu
Control Panel, Printers and My Computer in Explorer hidden and on Start Menu
Taskbar on the Start Menu hidden
Most Recently Used entries removed from Run history
Menus do not display upon right click on Taskbar, Start Button, Clock, or Taskbar icons
Menus do not display upon right-click of Desktop or Explorer's Results pane.
Only programs in Restrict subkey can be run
Remove Run command from Start menu

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

title says it all