good spot for a steal? Q-4 in SB

[youngfor3]

This is a play I have been making on the bubble lately when I sense weakness. Is this a good move? My thinking is CO will only call with a big hand because I have enough chips to cripple him if he calls and loses.

Also, button has been raising every time he even has a marginal hand. His limp screams of a weak hand that just wants to see a flop. Obviously BB can wake up with a hand.

Ultimate Bet No-Limit Hold'em Tourney, Big Blind is t150 (6 handed) converter

CO (t2295)
Button (t4310)
Hero (t1235)
BB (t2940)
UTG (t2675)
MP (t1545)

Preflop: Hero is SB with 4[img]/images/graemlins/club.gif[/img], Q[img]/images/graemlins/heart.gif[/img].
<font color="#666666">2 folds</font>, CO calls t150, Button calls t150, Hero goes all-in for 1235, <font color="#666666">1 fold</font>, CO folds, Button folds.