Hand from Bellagio $2500 super satellite - river decision

[NYWalker]

This is the first or second hand in the super. 5000 chips.

25/50, 3 limpers. I have Q[img]/images/graemlins/club.gif[/img] 7[img]/images/graemlins/club.gif[/img] at the button, limp. SB and BB both complete.
Flop Q[img]/images/graemlins/heart.gif[/img] 5[img]/images/graemlins/club.gif[/img]6[img]/images/graemlins/club.gif[/img]
SB bets 175. Fold to me. I raise to 525. SB calls.
Turn 2[img]/images/graemlins/diamond.gif[/img] SB checks, I check.
River 9[img]/images/graemlins/diamond.gif[/img] SB checks, hero?

Turn check was bad?

[GOONERCAM]

timid check on turn.i would value bet river here. maybe 600.