You are going to need a dedicated piece of software in order to run your web cam you will have to decide do you want to document it by video or still images taken a predetermined time frame example every 30 secs etc.
You will need plenty of space on your hard drive or a web site that you can upload the images to via the web cam software.
My New Avatar is in memory of Nancy my darling wife of 10 years who passed away on Monday November the 16th 2009 after an illness
My photo gallery http://thekiwi.org/photography/index.php