Once installed, there is no way to "back up" drivers or programs, other than to do a system image or total system backup using software developed for said purpose.
If it's a custom-built system, the drivers have to be spec'd by the motherboard manufacturers and their website is where one would normally get drivers for that board from. I say "normally" because some manufacturers do not retain a permanent inventory of all drivers for every board they have ever made.
Really...there is only one key driver needed for most of us...the NIC/network driver. I say that because...once that is installed, the user can go online and download drivers for the system or motherboard. The default video driver will do until the correct one is installed.
In any case...drivers are not extraordinarily large files and any user should be able to burn copies of them onto a CD for safekeeping.
What I do...I keep every CD that comes with a program or which accompanies a hardware item I purchase. I also keep copies of drivers which I have downloaded (for whatever reason) in clearly marked folders...and I store these folders on a separate partition on one of my storage hard drives/partitions (I have 5).
Any method which gives the user immediate access to drivers/programs which need to be installed...is a good system.