Critique this hand, please

[Iron Tigran]

First hand posted for review. Be gentle. ;o)

Hero is in Big Blind. 7d7h

It is folded around to MP, who checks (he posted a blind), folded to Small Blind, who raises. I call, MP calls.

Flop (board: 7c Jh 6d):

SB bets, I call, MP calls.

OK, so, I flopped a set and did not raise. This must be Big Mistake #1. I committed the sin of slow-playing. Right? I wanted to keep folks around. Always a risky thing to do, I know...

Turn (board: 7c Jh 6d Ad):

SB bets, I raise, MP calls. SB re-raises, I cap, MP calls, SB calls.

River (board: 7c Jh 6d Ad Qs):

SB bets, I call, MP calls.

Showdown:

SB shows Ac Jd.
I show 7d 7h.
MP mucks cards.
(MP has As 6s.)

So, my 3-of-a-kind beat two 2 Pair.

Second question: Was it bad to just call the River? My thought process was: SB raised pre-flop. He bet out on the flop. He capped the Turn. He bet out on the River. He is representing a big hand. The board has 3 overcards, which means 3 better sets could be out there. I am not worried about the straight being out there, just the sets.

My friend said I had to raise the river, but I felt too vulnerable.

Comment? And thanks!

--IT