Flopping second-nut flush, what's my goal?

[Cosimo]

Party Poker No-Limit Hold'em, $50 NL (9 handed) converter

Hero ($45)
MP3 ($35)
UTG ($100)

Hero (16/4) is weak-tight and doesn't let go of big pocket pairs often enough. [img]/images/graemlins/blush.gif[/img]

MP3 (27/7/2.7) has been pretty aggressive post-flop. I've seen him check-raise the PFR on a T-high flop with JT, check-raise a T77 flop with T9, and half-pot flopped trips thru the river. No bluffs, but he did raise big PF with 69s and bet 2/3 pot when he flopped second pair.

UTG (50/9/1.9) I haven't seen too much, but he's loose post-flop (I've seen him call ISDs vs half-pot bets). With low fold % (21/14/33) and high aggro, I think he's an action junkie, prone to do minbets like he did here.

Preflop: Hero is UTG+1 with 9[img]/images/graemlins/heart.gif[/img], K[img]/images/graemlins/heart.gif[/img]. SB posts a blind of $0.25.
UTG calls $0.50, Hero calls $0.50, <font color="#666666">2 folds</font>, <font color="#CC3333">MP3 raises to $1.75</font>, <font color="#666666">4 folds</font>, UTG calls $1.25, Hero calls $1.25.

This was a loose preflop call for me, but the table's PFR average was pretty low (under 3) so I was expecting to get in cheap. Should I have folded preflop, despite table passivity?

Flop: ($6) 7[img]/images/graemlins/heart.gif[/img], J[img]/images/graemlins/heart.gif[/img], Q[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">UTG bets $0.5</font>, Hero ...

These guys don't fold much, but I'm still worried about that A[img]/images/graemlins/heart.gif[/img] out there. What's my goal in situations like this? Potbet? Halfpot? Is $6 enough to just take down with a second-nut flush?

[iceman5]

Youre goal is to win a big pot which means you need to raise.

Make it $5 or $6. If one of them has the Ah theyre going to call and they only have 7 outs. They may even raise if they have AhJx or AhQx or AhAx. In which case you can push in.