Hi Steve,
My advice before you start buying expensive minimalist shoes is to find a grassy field and do some laps purely barefoot. Start with 10 minutes, then try 15 . . etc.
While you're doing this, use a transition shoe for your longer runs (but not to long!). The way I did it was to buy some racing flats and cut some of the heel off. They still have padding but there is virtually no arch support or motion control. Also they weigh less than 200 g. After a month or so as you get stronger then you can either get an expensive minimalist shoe or buy a dirt-cheap pair of shoes from tesco which are flat with little padding but will stop you from impaling yourself on a sharp rock.
The initial barefoot part is very import though and while you're doing it listen to your body very carefully for any sensory feed-back. Make sure youre form is perfect.
Here are some tips for your form:
1) make sure you're landing on your forefoot with your knees bent
2)make sure your back is straight
3)make sure you take little steps (it will feel rediculously small at first) that land almost directly below your centre of gravity
4)try to kick your feet back a bit after each stroke
A useful Phrase to remember is "Easy, Light, Smooth, Fast". i.e. Concentrate on making your new form feel natural, even if it's slow. Once you've got the hang of that concentrate on making your step light. Then concentrate on running on a horizontal line so that your neck and head don't go up and down as you run. If you can master all that you'll be fast already. (If you've read born to run you'll know it already. If you haven't read it buy it now.)
I hope you find this useful and not to long-winded.
Good luck and HAVE FUN!
Best,
Rob