I have old notebook with BIOS (not EFI) installed with Windows 8 RTM, want to install Ubuntu 12.10 by booting to a LiveCD.
Doing some research, I found method either to choose
Something Else or
Which method should I use?
As the other answer say, this method is the recommend one for those users that don't have the enough experience with partitions and OS installation.
In this method, you don't have to worry about the configurations, the Ubuntu installer will do all the complex work for you and you will be using Ubuntu in minutes.
Of course that both OS will exist separately and with own programs.
If you are one of those users how want all the things as they want to, configuring everything and choosing all the options to your way, this option is the one you should pick.
It will let you choice the use of the partitions (resizing, moving and allocating the free space).
In 95% of all the cases that is the smartest, and the fastest thing to do.
Full installation of UBUNTU to really experience UBUNTU. There's a lot support, like this site. You'll be amazed and stick to UBUNTU.