Backing up cache archives

[Gabriel Dragffy]

Hi, have installed much software, codecs and tools on my kubuntu system, there 
are many packages in my apt cache archive from the multiverse. How can I make 
a backup CD of all these so that if I later reinstall kubuntu, I can install 
all my software from the backup rather than re-download everything again? 
It's also useful as I may reinstall my computer (for whatever reason) in the 
absence of an internet connection and it seems a little unfair that I would 
have to miss out on all the fun.