I am awaiting the delivery of a new camcorder, and will be using iMovie for the first time (I have never done any video editing). I currently have a 2009 iMac running Lion, which has iMovie '09, and I did not know how to (or if I should) upgrade to the latest version of iMovie. So my questions are: 1. Is it necessary to upgrade? 2. Is it possible to upgrade the iMovie software on a 2009 iMac? 3. If I stay with iMovie '09 and start editing video, what will happen if I eventually upgrade to a newer version; will there be compatibility issues with older videos that were edited with an older version of iMovie? Sorry for the really basic (and probably stupid) questions; I really have no idea what I am doing! Thanks!