Big draw OOP against a possible steal

[TheMainEvent]

Just sat down

OK so I played passively on the flop, now I'm heads up with a villian who could be quite weak. I feel like I need to make a play for this pot, what is my plan for the turn?

Party Poker 1/2 Hold'em (9 max, 9 handed) FTR converter on zerodivide.cx

Preflop: Hero is BB with 6[img]/images/graemlins/heart.gif[/img], J[img]/images/graemlins/heart.gif[/img].
<font color="#666666">2 folds</font>, MP1 calls, MP2 calls, MP3 calls, CO calls, <font color="#666666">2 folds</font>, Hero checks.

Flop: (5.50 SB) 7[img]/images/graemlins/heart.gif[/img], 5[img]/images/graemlins/heart.gif[/img], Q[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(5 players)</font>
Hero checks, MP1 checks, MP2 checks, MP3 checks, <font color="#CC3333">CO bets</font>, Hero calls, MP1 folds, MP2 folds, MP3 folds.

Turn: (3.75 BB) 4[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">