if you value the time you put into loading all your media I would highly recommend you consider a RAID 1 solution; at least if a hard drive fails you can rebuild from the mirror (hopefully). There are a number of units out there that will do the trick, however there are some (DLINK DNS323 comes to mind) that have some issues that you may want to avoid. Do yourself a favour and do alot of research before making your choice.

In my case I went with a HP mv2010 (300G drive) and upgraded it myself to 2x500G drives. Total cost was $CDN630 and I got a spare 300G SATA II drive to play with. I couldn't be happier with the quality and performance.