You might just look for something that has less detail in it. When you reduce anything down to 50 x 50 pixels, if it has a lot of detail it doesn't reduce well.
You would need some sort of image file editing software. One that I use is Paint Shop Pro 7. If the image is animated you will need a package that can handle animated .gif files. Paint Shop Pro comes with Animation Shop. This is what I use for animated files.