(11$) A7s against aggressive bigstack

[mbman]

CO is aggressive and has been minraising quite a bit including the last three hands. My line of thinking was pretty much, I probably have the best hand, CO MIGHT fold if he is on total trash, I need chips if I am going to make it further in the tourney, SB + BB need something quite nice to call if I push. Comments?

PartyPoker $11 Regular Tournament, Big Blind is t200 (5 handed) Converter on pregopoker.com

UTG (t5298)
CO (t8511)
Hero (t1457)
SB (t2050)
BB (t2684)

Preflop: Hero is in Button with 7[img]/images/graemlins/club.gif[/img] A[img]/images/graemlins/club.gif[/img]
<font color="gray">UTG folds</font>, <font color="red">CO raises to t400</font>, <font color="red">Hero ??