Solid state drives are preferable to traditional motor-driven hard drives for pretty much everyone, but they won't improve your performance unless you work entirely with samples or samplers that stream off a hard drive like EastWest's Play.
Solid State drives will only increase the speed at which data can be read off the hard drive, and the speed at which your computer starts up. There are other benefits (longer life, less prone to failure, smaller size, etc) but if you're looking to improve your computer's performance you'd want to increase your RAM or improve your processer.