http://www.sportsshoes.com/
Start with that website, patel.
They do a guide to what sort of shoes you should need. First things first, you should do the "footprint" test (there's a picture guide on the site) - it tells you from your footprint what type you need
http://www.sportsshoes.com/advice/choosing-run ning-shoes
You'll need to know what type of surface you're going to be training on. Pavement/road will need either Cushioned, Support orControl shoes - they'll have a sole pattern that should point toward the toe). They'll be OK for the gym too for a treadmill.
Off-Road shoes have a different sole pattern to maximise grip and should be avoided as they won't provide the right support.
The best brands are Asics, Adidas, Brooks, Mizuno, New Balance, Reebok & Saucony. Drop sportsshoes an e-mail or ring your local JJB Sports store - they could give you some good advice. Yes, I do work for JJB ;-)