100NL - AA on a KK board

[kokiri]

Advice on all streets welcome. Fold river?

villain is 44/12 over 100 hands but seemed reasonable post flop.

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

MP ($106.80)
CO ($56.58)
Button ($87.45)
SB ($235.07)
BB ($339.68)
Hero ($114.81)

Preflop: Hero is UTG with A[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/club.gif[/img]. SB posts a blind of $0.50.
<font color="#CC3333">Hero raises to $4</font>, <font color="#666666">3 folds</font>, SB (poster) calls $3.50, <font color="#666666">1 fold</font>.

Flop: ($9) K[img]/images/graemlins/diamond.gif[/img], 5[img]/images/graemlins/club.gif[/img], K[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
SB checks, Hero checks.

<font color="blue"> Wa/Wb - checking might get a bet from an underpair, betting risks a C/R </font>

Turn: ($9) 9[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">SB bets $5</font>, Hero calls $5.

<font color="blue">could be a FD, k, small PP, bluff, pretty much anything.</font>

River: ($19) 9[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">SB bets $15</font>,

<font color="blue">this card kinda sucks - low pp's got counterfitted, FD hit, and we're behind a 9 now. is he ever betting a worse hand?</font>

Final Pot: $49