If you go to to the top bar to System -> Administration -> System monitor you will find the task manager you are looking for.
Now you may want to bind it to ctrl + alt + delete. Simply run this in your terminal window:
gconftool-2 -t str --set /apps/metacity/global_keybindings/run_command_1 "<Control><Alt>Delete"You can also go to System -> Preferences -> Keyboard shortcuts and set a shortcut in there. You will be running "gnome-system-monitor"
gconftool-2 -t str --set /apps/metacity/keybinding_commands/command_1 "gnome-system-monitor"