Got me an older movie on AVI and while the overall quality is good, it's a bit fuzzy. I have three tools available to me to fix it and I'm always up to learn about more. I've got AVIDemux with ASharp, which is three settings I know nothing about. They are Threshold, Strength and Block Adaptive, plus a check box for High Quality Block filtering. VirtualDub's method is about the easiest with only a slider to use, though I'm not sure how much good it did overall. Finally I have Blaze Media Pro and under their sharpening feature there's three sliders, Amount, which doesn't seem to move, Radius and Threshold.
There really isn't much you can do to get rid of the fuzzyness, unless you can get your hands on the original dvd files and convert them to avi. Otherwise, what you possibly d/l and want to burn to a dvd won't get much better.