Middle Set on a coordinated board

[Hoi Polloi]

Should I pop the river here? Or 3-bet the turn?

Villain is playing 1/2 his hands and raising 1/4 of those pre-flop. Very passive post-flop until this hand.

Party Poker 2/4 Hold'em (8 handed) converter

Preflop: Hero is MP1 with 7[img]/images/graemlins/heart.gif[/img], 7[img]/images/graemlins/diamond.gif[/img].
<font color="#666666">2 folds</font>, <font color="#CC3333">Hero raises</font>, <font color="#666666">2 folds</font>, Button calls, <font color="#666666">1 fold</font>, BB calls.

Flop: (6.50 SB) 6[img]/images/graemlins/club.gif[/img], 7[img]/images/graemlins/spade.gif[/img], T[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
BB checks, <font color="#CC3333">Hero bets</font>, Button calls, BB calls.

Turn: (4.75 BB) 5[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
BB checks, <font color="#CC3333">Hero bets</font>, <font color="#CC3333">Button raises</font>, BB folds, Hero calls.

River: (8.75 BB) 3[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">Button bets</font>, Hero calls.

Final Pot: 10.75 BB

BTW: sweet table -- loose and passive. This first time I raised pre-flop everybody folded so fast you would have thought I'd taken a dump on the table. They learned to hold their noses as the evening wore on.