Party 50nl (6 handed) - Do I call w/tpwk on river getting 5 to 1?

[CarlSpackler]

This is my first orbit at the table, so I have no reads. I bet about half the pot on the turn after the third spade fell, to find out where I was at. With the board pairing a 7 on the river, I couldn't think of a hand the villain had that I could beat. There's $20.25 in the pot on the river, so I'm getting 5 to 1 on my call. Is there any way I'm ahead of the villain more than 20% of the time here?

Table Table 65849 (6 max) (Real Money) -- Seat 1 is the button
Total number of players : 6
Seat 1: lurio ( $15.65)
Seat 2: Bristow99951 ( $12.10)
Seat 3: HERO ( $50)
Seat 4: deathends ( $71.52)
Seat 5: phenomenalli ( $40.85)
Seat 6: mr_hat187 ( $20.50)
Bristow99951 posts small blind (0.25)
HERO posts big blind (0.50)
mr_hat187 posts big blind + dead (0.75)
** Dealing down cards **
Dealt to HERO [ 5[img]/images/graemlins/club.gif[/img], Q[img]/images/graemlins/heart.gif[/img] ]
deathends folds.
phenomenalli folds.
mr_hat187 checks.
lurio calls (0.50)
Bristow99951 calls (0.25)
HERO checks.
** Dealing Flop ** : [ 8[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/spade.gif[/img], 7[img]/images/graemlins/spade.gif[/img] ]
Bristow99951 checks.
HERO bets (2)
mr_hat187 folds.
lurio calls (2)
Bristow99951 calls (2)
** Dealing Turn ** : [ 5[img]/images/graemlins/spade.gif[/img] ]
Bristow99951 checks.
HERO bets (4)
lurio calls (4)
Bristow99951 folds.
** Dealing River ** : [ 7[img]/images/graemlins/club.gif[/img] ]
HERO checks.
lurio bets (4)
HERO ???