Hi foxy mars,
I have seen this plan work wonders for increasing stamina up to 15 k a week with no problems at all:
Cool Running :: The Couch-to-5K Running Plan
It is complex to follow, but works like magic.
I use Asics trainers. However, I would recommend you visit a good running shop for advice, as everybody's requirements are different (I'm not talking about JJB Sports and the like, I mean a shop with trained staff
!).
Ash