You only need RAID 1 if you must have the computer up at all times, like with businesses. If you're not worried about this, then just utilize a backup.
In this case, you can have two drives installed internally so you only backup media files and documents or you can have an external hard drive to do the same.
If you're terrified that something may happen to your data you can purchase a hard drive dock ($25 at geeks.com) and after backup remove the drive and store it somewhere else.
With each of these above options, though, your backup drive will still be susceptible to viruses, etc. Thus, the best backup option is offsite, where you pay a monthly fee to have it automatically backup during the night.
But for most users a second backup drive is adequate, but you must realize that if someone steals your computer or your house floods or catches fire you will lose everything. Thus, an offsite backup is the preferred method.