Buying SSDs came up at Velocity today, and got it's own 5 minute presentation during the plenary presentations that's well worth watching. (PG-13, Language)

Buy an SSD if you value your own time. You don't understand what you're missing, and you should be be backing up anyways. It's not about reliability, it's about huge speed improvements. I also love that my laptop isn't a vibrating gyroscope anymore, even though it had never bothered me before.