If you want to store it securely and remotely, then I can highly recommend
strongspace.
Otherwise, as khana suggests, get an external hard drive to serve as a backup for your stuff. If you decide to go down this route, just go for the largest size drive you can reasonably afford, with a USB2 connection. Even if the drive is far larger than your current music and photo library, just remember that you will end up filling it one day, sooner than you think.
Else you could burn everything to CD or DVD, but that could become time consuming and hassle.
Personally I do all three, but the DVD option only has my essential documents that I can't replicate from anywhere else (for example, most of my music collection on the computer is from my CDs), so I only update that once a month or two.