OS X Startup Manager - booting from a CD

I need to diagnose my iMac and figure out how hosed my hard drive really is.

In Windows I knew to press F8 during system boot to get the boot manage. How can I do the same on my Mac?

• Press Option during startup Starts into Startup Manager, where you can select a Mac OS X volume to start from. Note: Press N to make the the first bootable Network volume appear as well.

• Press C during startup Start up from a bootable CD or DVD, such as the Mac OS X Install disc that came with the computer.

• Press D during startup Start up in Apple Hardware Test (AHT) (make sure the install DVD is in the computer.)

• Option-Command-Shift-Delete - Bypass primary startup volume and seek a different startup volume.

Cristiano Pierry