With no moving parts, they're quieter, more reliable and much faster. They're also a bit more expensive, but costs are now down to a level that makes them worthy of consideration.
The downside of SSDs is that they can be a pain to fit. Plugging them into the machine is often easy enough, but getting all your applications and documents transferred from the old drive can be troublesome – especially if you're working on a laptop which can't accommodate both drives at once.
