I have done both. When I hold down the "C" key it pauses for a few seconds while the cd spins and then the flashing folder icon appears.
Could be you have the wrong cd/dvd. The mac will only boot a supported cd/dvd for your machine. The flashing question mark indicdates your machine could not find a valid os.
When I hold down the "option" key for the startup manager the cursor comes up and moves but the actually manager doesn't come up no matter how long I leave the laptop on.
Not sure. Could be your machine does not support the startup manager. You would think the machine would ignore the key.
Where did you get the dvd? What is the number on the DVD?
What machine do you have anyway?
This site provides more information, but lacks security.
"A serial number is a unique, identifying number or group of numbers and letters assigned to an individual piece of hardware or software. It's used for various things depending on the product / brand but what is your Mac's serial number for and more importantly... what is it hiding and what can it do for you ?"
http://www.appleserialnumberinfo.com/Desktop/index.php
or
This site provides more information, but lacks security too.
"A serial number is a unique, identifying number or group of numbers and letters assigned to an individual piece of hardware or software. It's used for various things depending on the product / brand but what is your Mac's serial number for and more importantly... what is it hiding and what can it do for you ?"
http://www.appleserialnumberinfo.com/Desktop/index.php
http://www.chipmunk.nl/klantenservice/applemodel.html
( hint by K Shaffer )