Good advice from both above.
The hurting shoes thing is something that strikes runners as well and for the reasons listed by Setanta. Wrong size.
I ran for a year, fighting back against excess rubbing on the inside of my right foot and chaffing on my Achilles on my left. Couldn't figure it out because the shoes were the size I had always worn :10.5 . (Dat's me.)
Finally went to a really good running store whose employees didn't curl their lip at this 'light-truck model' of a runner and had my feet fitted into a pair of good shoes. um. Size 11.
They felt H U G E. In my running jounrnal, I dubbed them "Bigfoot" (you name each pair of running shoes so you can keep track of the wear and mileage on each.
I know, talk about obsession. My current pair is Glojack because the soles glow in the darkness. Sad. Yes.)
ANYway, foot problems disappeared. Gone. can run for miles with no chaffing. Huh. Sometimes experts are experts.
The saying in fashion is fit is everything.
Go to a good shoe store.
Watch how all the salespeople work (who is giving people the rush job? unuh. ) pick one and get fitted.