Well i found this out when i was in high school trying to figure out work arounds for their horrific security.
I'm sure someone else has found this out as well but i think it comes in handy from time to time so i figured i'd share it.
For those of you that didnt know already sethc.exe is sticky keys, so replacing it with CMD allows you to open CMD by hitting shift 5 times.

Note: if you try this on Windows Vista or Windows 7 you must first take ownership and then you must set permissions. If you try this on Windows XP skip this part because you dont need to take ownership or set any permissions
To take ownership and to set the permissions needed go to C:\Windows\System32
Step 1: find sethc.exe, right click and choose properties
Step 2: go to the 'security tab'
Step 3: click advanced and go to the 'owner tab'
Step 4: click edit choose the admin account then click apply
Step 5: go back to properties of sethc.exe and then the 'security tab'
step 6: click edit choose the same user you used to take ownership then put a checkmark in the 'full control' box under allow then apply
Step 1: go to C:\Windows\System32
Step 2: Find sethc.exe and delete it
Step 2: Find CMD.exe (copy it to desktop [dont make a shortcut])
Step 3: rename the copied CMD to sethc.exe
step 4: copy sethc.exe to C:\Windows\System32
Now hit shift 5 times and command prompt will open up, do this at windows,novell, etcetera login screen and command prompt will open up with admin rights
I'm sure someone else has found this out as well but i think it comes in handy from time to time so i figured i'd share it.
For those of you that didnt know already sethc.exe is sticky keys, so replacing it with CMD allows you to open CMD by hitting shift 5 times.

Note: if you try this on Windows Vista or Windows 7 you must first take ownership and then you must set permissions. If you try this on Windows XP skip this part because you dont need to take ownership or set any permissions
To take ownership and to set the permissions needed go to C:\Windows\System32
Step 1: find sethc.exe, right click and choose properties
Step 2: go to the 'security tab'
Step 3: click advanced and go to the 'owner tab'
Step 4: click edit choose the admin account then click apply
Step 5: go back to properties of sethc.exe and then the 'security tab'
step 6: click edit choose the same user you used to take ownership then put a checkmark in the 'full control' box under allow then apply
Step 1: go to C:\Windows\System32
Step 2: Find sethc.exe and delete it
Step 2: Find CMD.exe (copy it to desktop [dont make a shortcut])
Step 3: rename the copied CMD to sethc.exe
step 4: copy sethc.exe to C:\Windows\System32
Now hit shift 5 times and command prompt will open up, do this at windows,novell, etcetera login screen and command prompt will open up with admin rights