Here are two free screen capture tools that work decently well for small tasks:
1. CamStudio 2.0: Open Source software that comes with Visual Studio solution, and Win32 installation package. It works very well. Can capture to .AVI, and has a tool to convert AVI file to .SWF file and a HTML template to embed the Flash file. The captured file size is big. 40 seconds capture generated 20MByte AVI file and 1.5MByte SWF file.
SourceForge Host: http://sourceforge.net/projects/camstudio/
CamStudio - Free Streaming Video Desktop Recording Software: read the "Issues" section on this page. You will need to manually edit the generated HTML template in order for it to play in Firefox or Netscape.
2. Windows Media Encoder: Free Microsoft tool for video capture and editing. Capture result is WMV file format. File size is very small. But I recommend to use at least medium quality option which will generate a 500 KByte WMV file for 40 seconds capture.
My environment: Windows XP Professional, Dual Monitor