I know many people who use assorted ‘screencasting’ tools (Captivate, Camtasia, Firefly, etc.), and my guess is that very few of these people give much thought to the hardware they use for their projects. Hardware has a huge impact, and can be the difference between a successful screencast session and a computer that keeps crashing.
This author gives a nice simple overview of the topic, and also gives some practical tips about creating screencasts. Read “Screencast Success“