The key to keeping your data safe is keeping a lot of copies. I do work in IT and I have seen pretty much everything go bad. The key is not suffering catastrophic data loss, where you can't recover it. Just 1 device or backing up to CD once in a while isn't very reliable really. LaCie is ofted touted as a reliable HD brand, I saw 2 of their "rugged" drives (which are significantly more expensive than their normal ones) die without abuse in 1 week. Consequently, I've seen people on forums ripping on the WD externals, and I have 2 of the 500 gig ones I use all the time with no problems. Personally I choose WD most of the time because short of boutique HD solutions, WD drives are ALWAYS the most reliable desktop drives at every company I've ever worked at. I would never buy a Maxtor, Hitachi, IBM, or any of the non high-end Seagate drives.
There are quite a lot of options to have nearly 100% reliability of your data, but none of them are affordable or "set it and forget it". There's people that work full-time swapping tapes and making sure systems like those stay up. For home use, I think the most cost effective system would be to store all your important data on at least 2 HD's (preferably a mirror set), and backing up the really important stuff to DVD's as regularly as needed. Ideally burn multiple copies of those DVD backups and store them in multiple locations (ie your house, your office, a friends house, safe deposit box).