A good laydown

I'm playing terribly at the moment. The following was from a hand a few days ago, where I think I made an excellent laydown.

Full Tilt Poker $0.25/$0.50 No Limit Hold'em - 7 players
The Official DeucesCracked.com Hand History Converter

Hero (UTG+1): $81.40
MP: $55.10
CO: $97.25 - VERY LAGy player.
BTN: $24.35
SB: $50.00
BB: $20.50
UTG: $14.85

Pre Flop: ($0.75) Hero is UTG+1 with Tc 9c
UTG raises to $1.75, Hero calls $1.75, 1 fold, CO calls $1.75, BTN calls $1.75, 2 folds
Not a normal call in this spot, but an early raise gives potential that if I call, there will be additional callers. The CO had been calling wide as well, and T9s plays well in a multi way pot.

Flop: ($7.75) 4s 3c 7c (4 players)
UTG checks, Hero checks, CO bets $3, BTN folds, UTG calls $3, Hero calls $3
CO bets at the flop, which is not a normal play for him. I had found that when he had made hands, he'd bet, and with air, he'd check. I put him on a made hand, but with the flush draw & possible overs, I make the call. Particularly, I'm getting the UTG to come along.

Turn: ($16.75) 2c (3 players)
UTG checks, Hero bets $10, CO calls $10, UTG raises to $10.10 all in, Hero calls $0.10, CO calls $0.10
I hit my flush, and want to get value. With CO calling, I suspect he is a lot stronger than a 1 pair hand. I don't know why, but I felt, at the time, he had a set.

River: ($47.05) 4h (3 players - 1 is all in)
Hero checks, CO bets $47.05, Hero folds
As the board pairs, I'm certain my flush has been beaten by a boat. I can't imagine him committing 100 BBs without the strongest hands.

Final Pot: $47.05
CO shows 3s 3h (a full house, Threes full of Fours)
UTG mucks Ah Kc
CO wins $44.70
(Rake: $2.35)