Disable Task Manager

NOTE: This method will work for all Vista versions.
1. Open the Start Menu.
2. In the white line (Start Search) area, type regedit and press Enter.
3. Click on the Continue button in the UAC prompt.

4. In regedit, go to:
NOTE: If you do not have System, then right click on Polices and click on New and Key. Type System and press Enter.
Code:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System

5. To Disable Task Manager -
A) In the right pane, right click on a empty area and click on New and DWORD (32-bit) Value and type DisableTaskMgr and press Enter.
B) Right click on DisableTaskMgr and click on Modify.
C) Type 1 and click on OK.

6. To Enable Task Manager -
A) In the right pane, right click on DisableTaskMgr and click on Delete.
B) Click on Yes to confirm delete.

7. Close regedit.