Once the install process starts and you get the initial boot: prompt, as long as you have fairly standard hardware, here are the most common responses:
boot: ENTER standard, graphical install boot: linux text non-graphical install boot: linux lowres low resolution (640x480) boot: linux mediacheck verify (md5sum) CDs first
You can also do nothing, which will eventually cause a timeout and is equivalent to just hitting ENTER. There are, of course, numerous other possibilities, but these should cover you 98% of the time.