how to develop an active desktop application in c#

Question

i want to develop a nice thing that will be on the desktop (like an active desktop) something like this:

http://www.tinnes.org.uk/desktopcalendar/about.htm

or this:

http://www.xemico.com/adc/screenshots.html

Edit:
That gadget should be common for XP,Vista, Windows 7 and that gadget size should be adjustable

Answer 1

If you're using vista or seven you likely want develop a desktop gadget.

Look at this answer for some hints: http://stackoverflow.com/questions/1171588/c-tutorial-to-write-gadgets