One of villain's first hands at the table...I put him on an overpair, what do we do on turn?

Game #2699406553: Hold'em NL ($0.25/$0.50) - 2006/12/06 - 04:21:29 (DST)
Table "Lundu" Seat 2 is the button.
Seat 1: Per0303 ($10 in chips)
Seat 2: bosse124 ($61.80 in chips)
Seat 3: lambsie ($76.20 in chips)
Seat 4: saltjoe ($37.65 in chips)
Seat 5: HERO ($212.55 in chips)
Seat 6: VILLAIN ($40.75 in chips)
lambsie: posts small blind $0.25
saltjoe: posts big blind $0.50
----- HOLE CARDS -----
dealt to HERO [3d 3s]
HERO: raises to $2
VILLAIN: raises to $6
Per0303: folds
bosse124: folds
lambsie: folds
saltjoe: folds
HERO: calls $4
----- FLOP ----- [4h 6h 5d]
HERO: checks
VILLAIN: bets $8.50
HERO: ??