You shouldn't need to do anything special to get coins from that wallet.  Just install the newest wallet (Desktop PiggyBank), run it, close it, then copy your old wallet.dat over the newer one.  That's for New PiggyCoin [PIGGY].

If you're talking about the old proof-of-work PIG, then you're out of luck I'm afraid, as that coin is defunct now.  There was a coin swap to New PiggyCoin which went on for over a year, but we felt we had to end it eventually.