I'm often asked what shoes I personally recommend to help stay injury free while running (on the 100 day plan) so I'll add a little bit about it at the end of these Q and A's.
Good shoes are crucial if you want to stay injury free during your marathon journey. In general, the best is to find a shoe that fits your feet according to your foot type.
However, these three shoes will do an excellent job with their mild correction - and will work for most runners :
1. Asics Gel Kayano (click for zappos reviews for other runners views)
The legandary shoe from Asics. You cannot go wrong with this one.
The most sold running shoes ever - and by every model seems to get better and better. About the same weight as the Kayano but the fit is a little bit different.
The 2150 is a great alternative for the faster work you'll be doing in the 100 day plan. It is one of the few shoes that "feels" like a lightweight one but at the same time has more than enough stabilty to prevent injuries with the marathon type length of some of the interval sessions.
A tips for international (non-US) runners : check out roadrunnerssports.com :
Example : Asics Kayano (RoadRunnerssports) they ship worldwide and it can really save you some money on your shoes.