Jasc, the guys that make Paint Shop Pro, have a product called Animation Shop 3 that can directly import a set of .png files and output movie files in several formats (including .avi, .gif). I've used this to create animations for use in Powerpoint presentations that are quite reasonable. The software only costs $39 and is bundled with the version of Paint Shop Pro 7 that is currently available. A significant savings over Adobe Premiere and it eliminates the step of having to convert file formats using ImageMagick (althoug Paint Shop Pro 7 can also batch convert between file formats).
Worth a look if you are interested in presenting your PyMol animations.
