You can use SyncToy from Microsoft for free.
You can setup a scheduled task, only do certain files, folders, or file extensions.
Also, since it's a "sync" utility, you can actually use it to keep copies of your most up to date change, reguardless of what computer you were using to make the change.
It's has a ton of possibilites. I use it for keeping my Music files sync'ed between my home computer, my laptop, my wife's laptop, and my media center PC. So if I change the ID3 tags on any of those boxes, the changes get cascaded.
Works well for photo's and video's as well, assuming you have additional PC's in your house you can back up to.
For offsite / more permanent backups, I used to backup to DVD, but with Hard Drives being sooooooooooo cheap, I just go buy the sale of the week harddrive at Fry's. Stick it in a USB 2 enclosure, copy everything over, and then file the hard drive away at work.
SyncToy Download Page