I suggest jacking up the front and rear on jack stands. But first, you'll need to take off the mower deck. It really isn't that hard - there are only pins to remove. Just remember what goes where. Then, jack it up. Disconnect the sterring likages to allow belt removal/replacement. Look how the belt goes around the pulleys (hopefully your belt is still on there.) You'll need to loosen some of the pulleys a bit to allow the old and new belts to slip over. Main advice: Take your time and give some time - be patient. It isn't fun, but not that hard either.
Tim, November 2007