PokerPat,

If I had hit a set of 5's, my line would have been:

-Lead out probe bet (1/2 pot, same as above)
-Villian reraises potsize (same as above)

Then, my action depends on the Other Guy. If he calls, it indicates a draw, and the pot is already big enough for me to make a move. If he folds, I would simply flatcall and make my move against the overpair on the turn.