Archived - Apple Remote Desktop: How to send Ctrl-Alt-Del to a PC
If you use Remote Desktop to administer a PC that's running VNC, you may be wondering how to send the Ctrl-Alt-Del command (Control-Alternate-Delete) from a Mac to the PC. Though Mac and PC key mapping differs, you can use an alternate key combination in Remote Desktop 2.0 and later to send the command.
For full-size (desktop) keyboards, use Control-Option-Forward Delete.
For abbreviated keyboards (on portable computers), use Function-Control-Option-Command-Delete.