77, against donkish player

[Rounder101]

Villain is kinda donkish, Ive seen him make this limp/calls like 3 times in early position, and in one of them he went showed QT and lost with midpair a small pot.
At that session he was 40/11/3 for little less than 100 hands.

Full Tilt No-Limit Hold'em, $1 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

SB ($74.45)
BB ($254.30)
UTG ($57.10)
Hero ($116.15)
CO ($83)
Button ($95.75)

Preflop: Hero is MP with 7[img]/images/graemlins/club.gif[/img], 7[img]/images/graemlins/heart.gif[/img].
UTG calls $1, <font color="#CC3333">Hero raises to $4.5</font>, <font color="#666666">2 folds</font>, SB calls $4, <font color="#666666">1 fold</font>, UTG calls $3.50.

Flop: ($14.50) 8[img]/images/graemlins/spade.gif[/img], 5[img]/images/graemlins/diamond.gif[/img], 4[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">UTG bets $6</font>, <font color="#CC3333">Hero raises to $18</font>, SB folds, UTG calls $12.

Turn: ($50.50) 2[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">UTG bets $11</font>, Hero calls $11.

River: ($72.50) 4[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">UTG bets $23.6 (All-In)</font>, Hero??

Comments on all streets apreciated