It depends on what you you are doing, how much time you intend to invest, and what system resources you have. As far as codecs, I've had the best luck with the DivX 4.12 codec. Clean, crisp, and a reasonable file size. Many who do animations -will- render the frames out as seperate stills, and compile them in something like QT Pro; the main reason for this is the amount of time animation rendering can take, and the odds of a gremlin aborting the render go up the longer it takes (There is also the fact that you can, if you are truly a masochist, take the seperate frames into a paint program and adjust or add extra effects). By saving the raw frames, you can restart the render from the last good frame, and continue onward. The one thing you will need to have is -plenty- of hard drive space for the seperate frames. I tend to render with the DivX 4.12 codec, but then I also have a 3 node render garden to play with (soon to be 4; you can build a basic box for a couple of hundred dollars if you shop wisely, and settle for a couple of slices back from the bleeding edge. It also allows you to have secondary applications on one of the renderboxes, so you can surf or do other things and not disturb the controller).