See this Apple note, which applies to OS X 10.7 Lion as well. This Apple note applies to OS X 10.6 and earlier but provides a little more information. When they talk about booting from CD, that's a boot with command and r keys held down in OS X 10.7 Lion.
This site contains user submitted content, comments and opinions and is for informational purposes only.
Apple disclaims any and all liability for the acts, omissions and conduct of any third parties in connection with or related to your use of the site.