Since I get asked a lot, here’s my rundown of screencast tools –
PC – Camstudio: Free and can get you started
PC – Camtasia: $299 but has bells and whistles that most people want after doing it for a while (e.g. pan and scan)
PC – Captivate: $699. Like powerpoint on steroids, lets you capture screen sequences and create demos or interactive simulations — then outputs Flash movies that you can put on the web (.swf) or edit in the Flash IDE when installed on the same machine (.fla).
Mac – iShowU: $20
Mac – Snapz Pro: $69
Mac – Screencast: $29. Here’s a recent review of this third Mac tool in relation to the first two.