Cain "should", if healthy, get 200+ innings this year.
Hamels will probably be taken a little slower this year because of his injured past and the lack of innings he has thrown the last few years. Less innings means less stats (W and SO totals) I'd expect 170-180 innings IF healthy.
I think they are both equally talented, but for this year I'm going to go with Cain because I know he is at a point where he can take on a decent work load (190+ IP the last 2 seasons) and to my knowledge hasn't had any significant injuries to worry about.
.... oh yeah, Cain has an easier division to deal with and a better home pitchers park!
Give me Cain in '07........ you'll have to get back to me in regards to '08 and beyond