I know a lot of you will say i should have folded preflop, but i knew this guy wouldn't lay down big pair if i hit.
No, I would actually encourage calls like this because your implied odds are huge, especially at the lower limits where people can't lay down an over pair. Case in point...

PokerStars Game #2191113857: Hold'em No Limit ($0.50/$1.00) - 2005/07/26 - 10:34:30
(ET)
Table 'Fama IV' Seat #8 is the button
Seat 1: shamo ($46.30 in chips)
Seat 3: DocSlapnut ($60.80 in chips)
Seat 4: el vikingo ($49.75 in chips)
Seat 5: exacta ($99.00 in chips)
Seat 6: NutsInYoEye ($97.70 in chips)
Seat 7: thegroin ($281.30 in chips)
Seat 8: Pulp_X ($97.10 in chips)
Seat 9: ammed ($33.20 in chips)
ammed: posts small blind $0.50
shamo: posts big blind $1.00
*** HOLE CARDS ***
Dealt to NutsInYoEye [4s 4c]
juanita3 has returned
DocSlapnut: calls $1.00
el vikingo: calls $1.00
exacta: raises $2 to $3.00
NutsInYoEye: calls $3.00
thegroin: raises $7 to $10
Pulp_X: calls $10
ammed: calls $9.50
shamo: folds
DocSlapnut: folds
el vikingo: folds
exacta: calls $7
NutsInYoEye: calls $7
*** FLOP *** [2s 4d 7c]
ammed: checks
exacta: bets $7
NutsInYoEye: calls $7
thegroin: raises $33 to $40
Pulp_X: folds
ammed: folds
exacta: folds
NutsInYoEye: calls $33
*** TURN *** [2s 4d 7c] [6s]
NutsInYoEye: checks
thegroin: bets $231.30 and is all-in
NutsInYoEye: calls $47.70 and is all-in
*** RIVER *** [2s 4d 7c 6s] [Ks]
*** SHOW DOWN ***
NutsInYoEye: shows [4s 4c] (three of a kind, Fours)
thegroin: mucks hand
NutsInYoEye collected $219.40 from pot
*** SUMMARY ***
Total pot $222.40| Rake $3
Board [2s 4d 7c 6s Ks]
Seat 1: shamo (big blind) folded before Flop
Seat 3: DocSlapnut folded before Flop
Seat 4: el vikingo folded before Flop
Seat 5: exacta folded on the Flop
Seat 6: NutsInYoEye showed [4s 4c] and won ($219.40) with three of a kind, Fours
Seat 7: thegroin mucked [Qd Qs]
Seat 8: Pulp_X (button) folded on the Flop
Seat 9: ammed (small blind) folded on the Flop

I'll call 3x-5x BB bets pre-flop with small pocket pairs, especially I think I think that someone has a higher pocket pair like QQ-AA. With a rag flop, pretty much anyone will throw out a pot sized bet or even overbet when they have an overpair. Sets are hard to detect to begin with, and sometimes even more so when people don't expect little cards when you call a decent pre-flop bet. The hand I just posted is a little weird with so many other callers, but you get the idea.

When you find yourself in a situation like this where you hit a small set and you are confident in an over pair, then LEAD out if you're first to act. If you use the weak lead and bet around 1/3 - 1/2 the pot, the person with an over pair will almost always come over the top and usually pot commit themselves. You can then either re-raise and likely get a call or smooth call and wait for the turn to spring your trap.