http://southernfood.about.com/od/chi...r/bl80517l.htm
I've used that one before, although I made the 'spaghetti' sauce myself rather than using a jar.
Fry two large onions or a couple of shallots in a bit of sunflower oil, add in 4 crushed or chopped garlic cloves until the onions go soft, add in 2 tins of chopped tomatoes, heat until simmering. Add in some mixed herbs and a bit of Cayenne pepper for some heat and boom, easy sauce. Can also add in a splash of red wine as well, and reduce it down a bit.