This is not true; you don't have to download these programs every time you do an installation. If that is the common way you install PCs, then please look into CloneZilla, Remastersys, or the instructions for remastering a Linux Mint ISO: http://community.linuxmint.com/tutorial/view/918
. Basically, you can with any of these three create a bootable installer ISO of Linux Mint, but including your additional programs. You would only have to set up that image once and then you can repeatedly install it.
Another even easier option is to look in your /var/cache/apt/archives folder, where the downloaded packages are kept that you selected to install. You can copy these packages to another system, and install them there
Those are some options for not having to download packages repeatedly. If you need help with that, please post in the support section of the forums.