That NAS would work fine for what you want to do. But like Scott said redundancy is KEY! Put your photos on the NAS, burn them to DVD's and put copies of the DVD at your parent's house, friend's house, safe deposit box.
Also, hard drives are cheap so put them all on another cheapy external drive and stick that in the safe deposit box or friend's house too.
http://www.tigerdirect.com/applicati...079&CatId=4230
Photobucket pro costs a couple bucks a month (like literally $2 bucks) and offers unlimited photo storage, accessible from anywhere. You can set your albums to private and you have essentially a digital locker for your photos.
Dropbox or box.net is a bit more expensive but can work for your photos and videos.