For basic stuff, like critics, I use unfreez. Its free hence the name unfreez. Its quite easy, but they all the frames have to be saved as .gifs first. If you have something on the good side, unlike ms paint, for saving it works great. I'm not sure of the website of the top of my head but I know it is on download.com. I just 'got' Flash MX and it looks good too. I havent had time to mess around with it much yet.