Linux
If it's got an inbuilt webcam, it should also come with software pre-installed. My Compaq laptop has a webcam and a programme called Cyberlink YouCam, which I had to look for in the list of programmes. When the programme is opened, the webcam switches on (a little light lights up next to it) and... there's me on the screen, looking older and fatter than I ever imagined. Webcams are not flattering.
Also, if you've got a big enough hard drive and you want to try installing Ubuntu Linux for free, (you could try it by installing Ubuntu using WUBI - Windows Ubuntu Installer - as a Windows application) then free software can be downloaded to use your webcam in Ubuntu).
