For Debian at least, /var/cache/apt/archives/ holds the .deb files you download from the internet. So when it comes time to reinstall the system if you've downloaded mkisofs and cdrecord and have burned an image of that directory and its contents after yoou do the base insttall with the CD you can then use apt-get update to get you lists of updated files. Then when you want to install the stuff off the Cd you made, first do it with apt-get -nodownload install package so you can get a list of dependencies. Then run dpkg -i and key in all of those file names and you'll be able to minimize internet exposure until you've put your security software packages on and got them configured. I wonder if yum does some similar archiving in a single directory like debian does.
