Amethyst, if you have a bad style of running it might be best to go to a sports podiatrist first. They'll analyse your run and foot-fall and recommend what sort of running shoes to go for. There are a few running shoe shops that will do this, Active Feet in Prahran (Melbourne) has some podiatrists on staff. Cool Running Australia has a forum where you'll find recommendations on how, and where, to get best running shoes (link
My favourite shoe right now is the 'Rocket' by Earth Shoes. It's a bit weird compared to most running shoes because the heel is lower than the rest of the foot, but it's magnificent for my plantar fasciitis because it has great midsole cushioning.
I calculated my ideal running weight and it would be 57 kilos. It's scary that they recommend you don't run until you're within 3 kilos of that weight. 60kg is less than my goal weight! And as Court pointed out, it's a Catch-22. Running is a great way to lose weight, but you need to lose the weight before you can run! I had the same dilemma with my plantar fasciitis. It's a foot problem caused in part by being overweight. The best treatment is to lose weight. But if you have PF you are supposed to stay off your feet as much as possible which makes it difficult!