Most configuration settings are kept in the /etc directory. Drivers themselves are generally either compiled into the kernel or loaded as kernel modules from the /lib/modules area.
So you could backup these areas. If you have space on external media, it's probably better to do a full backup. This will take a long time the first time, but if you use backup software which incremental backups, subsequent backups won't take as long (assuming most of your system is the same between backups).
There are lots of backup solutions for Linux with very different features. Before anyone can recommend one, you need to answer some questions:
- What medium are you backing up to. DVDs? CDs? An external hard disk? Network Storage Device? Tape drive?
- Do you want to be able to do incremental backups (note, this is good for saving space if you want lots of snapshots of your data, but can complicate recovery)
- Do you want to be able to do your backups remotely?
- Do you want to generate a rescue disk which will restore your system even if it is so hosed it is unbootable?
- Is the system which you want to back up a high availability system which needs to keep running while you backup, or can you set it off and before bedtime and let it work on the machine unhindered?
- How much data needs to be backed up, and how often. You need to think about the initial size of the data, and the size of subsequent changes to that data.
In The Linux Action Show Episode 19
they discuss some backup solutions, which might be useful for you.