A slow death (or lessons in archving)

I have been using a 1TB My Book USB (backpack) hard drive as my principle archive location for my photo collection for several years now and it has worked very well. It is connect to PC being used as a media center so it is always on and has a wide screen LCD TV to view the photo directly on that computer (from the comfort of a couch, not quiet but close to the old 35mm slide show feel). The TV screen is a HD flat screen Sony Bravia, connected via a HDMI cable, so the photos are crisp, clean and at a good resolution, I had observed that that drive was getting slower and slower since I also put my itunes library on that disK. Terminally slow! Then quite by accident I noticed that I could not read a couple of photos, then another and others where so slow to respond. I decided it was time to copy everything to a newer backpack drive. Half a terra byte of photos and videos takes a fair while to copy (off a drive that is slowing anyway) and in that process I discovered a dozen files that I could not read. It was easy to find good copy in the two sets of CD/DVDs I make each month as backup. So no data was lost but it has forced me to rethink the strategy of only one archive on-line (ie on a constantly spinning hard disk).
A single library of photos is much easier to maintain. I’ll have to report soon on another experiment I had tried where I used different software on different computers to test their management capabilities. While the programs all worked well using a range of system was a confusing disaster, So I like the idea of a single “central” archive BUT that means the risk of only having a single copy. Using a raid system with mirror backup is one good option, and I do have a netgear stora for my business and thus has worked perfectly however it doesn’t really have the room. Another option is to use an online back service (i’m trying out iBackup, but there are many others). The third option is to use have two backpack drives and have your own scheduled SYNC process that routinely copies files to a second location ( I'm going to start with the reformatted my book on my home network for this.)
So which option have I choosen?
Despite the hard lesson learnt about using multiple photo management packages being a disaster. I will be using, or at least trying out, all three options, I’m splitting my collection into three 1. family & events (using a daily backup schedule to a secured private net location) privavy is important here.  2. video, the most rapidly expanding aspect of my collection (synced to the My Book, because the media center is where I’m most likely to view and work on video) and 3. everything else (mirrored on my stora).
Finally I’ve decided that my archive is not an archive at all, its my original collection, the “backup” CD/DVDs are really an archive and the the second live copy is my true backup.