It is enabled under Windows 7. Pressing Ctrl+Alt+Del simultaneously will give you options to Lock the computer, Switch to another user, Log Off the current account, Change password and Start the Task Manager.
On my steelseries merc if you have numlock turned on then the number pad on the side will only be numbers. That means if your delete key is on the numbers then it will not be activated until numlock is deactivated.
Quite obvious really but it's easy to forget if you're in a hurry
How to enable Ctrl + Alt + Del key to Windows 7?
Go to the start icon.
search and type the netplwiz command.
The User Accounts box opens with two tabs: Users and Advanced.
Next select the advanced tab.
The secure logon feature will now be enabled when you check “require users to press Ctrl + Alt + Delete.”
This is nominal security to be sure, but if you want it enabled, it is easy to do.