Over the last few weeks, I've made about 20 short video tutorials. To get the screen captures for these, I've been using a neat little tool: CamStudio. Despite being ultimately an Adobe product, it's free, it's open source, and it does the job on both Vista 64 and Windows 7.
It's capable of recording the audio from the app and from a microphone, so it's great for narrating as you demonstrate something, which is perfect for what I'm doing. Admittedly, I then re-dub it with a better script and a nicer voice, but it serves as a guide. Apart from that it's just really basic. Start recording, do whatever I'm doing, stop recording, render, and do everything else in post.
There are one or two down sides, as you'd expect from a free product. It's not great at handling huge amounts of data. Capturing my 1920x1080 resolution monitor it tends to run out of memory when trying to render anything more than about 4 minutes long, so I work in short bursts, and then save & render. That's just fine for my purposes though, because it gives me a chance to watch that segment and re-do any bits that went wrong without having to step back too far. The other irritant is that (ironically) Premiere doesn't like importing the avi files CamStudio puts out. However, I just run everything through Windows Movie maker, trim the start and end there, and output them at the target size, which takes just a couple of minutes, and means that everything is Premiere-ready.
So, it's not the greatest screencap tool ever, but it's good enough, and a lot cheaper than some of the alternatives.
Download it from http://camstudio.org/