How do you play the river here? Opponent has shown down some strong hands, and generally seems tight.

***** Hand History for Game 3221782289 *****
$25 PL Texas Hold'em - Sunday, December 18, 10:48:12 EDT 2005
Table Table 65068 (Real Money)
Seat 7 is the button
Total number of players : 10
Seat 1: Nugunz ( $32.26 )
Seat 2: fab39 ( $5.63 )
Seat 6: PILEDRIVER16 ( $25.65 )
Seat 7: EP_SHARK ( $23.70 )
Seat 9: Lukinyul ( $29.35 )
Seat 10: rcomst1217 ( $28.25 )
Seat 3: SAHDSC ( $22.60 )
Seat 8: liables406 ( $4.15 )
Seat 5: Chucktx64 ( $27.85 )
Seat 4: fakai_fa ( $5.65 )
liables406 posts small blind [$0.10].
Lukinyul posts big blind [$0.25].
** Dealing down cards **
Dealt to Nugunz [ 3s 3d ]
rcomst1217 calls [$0.25].
Nugunz calls [$0.25].
fab39 folds.
SAHDSC folds.
fakai_fa folds.
Chucktx64 calls [$0.25].
EP_SHARK folds.
liables406 folds.
Lukinyul checks.
** Dealing Flop ** [ 3c, 5s, 7h ]
Lukinyul checks.
rcomst1217 checks.
Nugunz checks.
Chucktx64 bets [$0.50].
Lukinyul folds.
rcomst1217 folds.
Nugunz calls [$0.50].
** Dealing Turn ** [ 4c ]
Nugunz checks.
Chucktx64 bets [$0.50].
Nugunz raises [$2].
Chucktx64 calls [$1.50].
** Dealing River ** [ 7d ]
Nugunz bets [$3].
Chucktx64 raises [$7].

Your move?......


Results below in white:

Nugunz raises [$17].
Chucktx64 is all-In [$18.10]
Nugunz calls [$5.10].
Nugunz shows [ 3s, 3d ] a full house, Threes full of sevens.
Chucktx64 shows [ 4s, 4d ] a full house, Fours full of sevens.
Chucktx64 wins $53.50 from the main pot with a full house, Fours full of sevens