I have yet to have a harddrive fail on me that I didn't do something malicious to. Taking care of your parts really isn't that difficult.
Harddrives have moving parts, and the ferrous material doesn't last forever. I've yet to have a harddrive fail before I moved its data to a fresh drive, but I've had many (at least 5) harddrives that I've owned long enough for them to die of normal wear. These days, I generally only buy WD Black drives, which come with a 5 year warranty, so I imagine those ones will last much longer.
I'd like to learn Xen, but we use VMWare at work so I'm used to it, and I've gotten accustomed to VMWare Server's stupid little quirks.
I'm using Virtual Box at home because it was free (read: easier to download) and does what I need. If I had the time to screw around with it, and another machine to play around with, I would love to learn Xen. Right now, my 3 machines all have their own purpose - my Linux box has to have 98% uptime, or I'll lose money, so that one's out. My main machine is for gaming, which I'm not willing to sacrifice. I could do it on my Mac, but the harddrive is so slow that backing up takes forever, so I just don't feel like doing it.