I have an Dell Inspiron 6400 who is running an windows 8 and i can't boot it with an CD with an WINDOWS ALL-IN-ONE SP 1 and I can't boot from this CD! Can anyone help me?

You must go into BIOS Setup and change the first boot device to "CD/DVD Drive" instead of Hard Drive which it's set to at the moment. Alternatively, press the appropriate key to bring up the Boot Menu and choose "CD/DVD Drive", then press <Enter>.
Your Dell manual should explain which keys to press for either of the above methods.
Why are you trying to install Windows 8 on this machine anyways? It wasn't even designed for 7, so I doubt it will have any drivers or support available for 8... http://support.dell.com/support/top...
You've been helped by a 15 year old.
Ok, then you should just press F12 when you see the Dell Screen, then just choose the CD drive from the menu there... You've been helped by a 15 year old.
