And given how cheap hard drives are (and how likely they are to eventually fail) it seems like that would almost always be a good investment.

Indeed. My /home directory is on a 1TB 3-way RAID 1. Because I am that paranoid about disk failure.

Interestingly, all three disks failed, because Newegg does not know how to ship them properly. Never buying disks from them again. The good news is that only two failed at the same time, so there was no data loss. And the replacement disks from the manufacturer, Samsung, have been chugging along for months just fine.

RAID on your desktop is nice. RAID on your server is mandatory. The total cost was $300 for one fucking terabyte. Just do it :)

I've purchased many hard drives from NewEgg, those same hard drives have been through two moves now and they are still going along strong. Not a single bad sector or anything along those lines.

OEM or retail? Retail disks have better packaging, but I bought OEM disks.

Mine came in plastic egg cartons with a few packing peanuts. I'm surprised they didn't shatter on their way across the country.

OEM, never retail since retail is always more expensive. Yep, same plastic egg cartons with a ton of packaging peanuts. Received 8 1 TB drives.

I agree with that: the cost of a few extra mirror disks is negligible compared to the amount of time one loses rebuilding a machine (OS + applications + configuration) from scratch.

Yet, all too often I come across people who don't want RAID1 because they can save $60 by not installing that second disk.

And if you are using linux LVM raid for your root partition, you should practice breaking a drive. It works, but best you find out how to deal with it before having to do some panic googling.

Also, I strongly recommend setting up mdadm in daemon mode to send you an email on failure as you can go days or weeks without noticing a degraded array. It's really easy to set up in most distros, so do it now (and don't forget to test it).