Lay Down a Full House?

This is from a hand that I played today, and I wanted to get some thoughts.

Background: This is a 0.50-1.00 Party table, and I just sat down - this is my first hand from BB. I was at the table for 4-5 hands before this, but there really wasn't much in the way of action to get a read.

Hand:
Party Poker No-Limit Hold'em, $ Hero (9 handed) internettexasholdem.com

SB ($49.50)
Hero ($50)
UTG ($48)
UTG+1 ($55.20)
MP1 ($43.70)
MP2 ($69.35)
MP3 ($51.95)
CO ($143.95)
Button ($48.50)

Preflop: Hero is BB with 8[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/club.gif[/img]. SB posts a blind of $0.25.
<font color="#666666">2 folds</font>, MP1 calls $0.50, <font color="#666666">1 fold</font>, MP3 calls $0.50, <font color="#666666">1 fold</font>, Button calls $0.50, <font color="#666666">1 fold</font>, Hero checks.

Flop: ($2.25) 9[img]/images/graemlins/heart.gif[/img], 8[img]/images/graemlins/club.gif[/img], K[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(4 players)</font>
Hero checks, MP1 checks, <font color="#CC3333">MP3 bets $2.15</font>, Button calls $2.15, <font color="#CC3333">Hero raises to $6</font>, MP1 folds, MP3 calls $3.85, Button calls $3.85.

Turn: ($20.25) 8[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets $12</font>, MP3 calls $45.45 (All-In), Button folds, Hero calls $31.50 (All-In).

River: ($109.20) 9[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players, 2 all-in)</font>

Final Pot: $109.20

You can all feel free to comment on any street, but in particular I am interested in comments on my all-in call on the turn.

I will post results and thought process (or lack thereof) after I get a couple of responses.

Thanks in advance for everyone's help.