Highly recommend that you invest in a couple of x-racing greyhounds. Two reasons:
1. they find cats a tasty snack and can catch them (personal experience). This has the effect of a) reducing the local moggie population and b) discouraging further visits from any other local moggies.
2. X-racers make fantastic pets. Eat anything, no great need for huge amounts of exercise, do not steal your beer, they are couch potatoes and keep you warm while watching the tv.

Hope this helps. If all else fails I can highly recommend a catapult loaded with Growmore pellets. If you miss the moggie, no harm done, a bit of extra nutrient for the garden.