goldfish compatible with puffers

Question
I'm an animal lover, but know nothing about fish.  A coworker with a goldfish in a tiny one gallon tank changed jobs, and gave me care of the fish.  I'm searching Craigslist for a bigger tank (that fish must be severely bored).  Came across a really good one, but it comes with some puffer fish (and some plants) that have been living for awhile in fresh water.  Would it be a good idea to have the goldfish and the puffers in the same tank?  Any potential problems with violence?  disease?  What might be some good techniques for changing the tank over, introducing the fish, etc. etc.  Any guidance would be very much appreciated.  Thanks so much.

Marilyn

Answer
A puffer would eat your goldfish a bite at a time.  Most puffers are brackish, which means they live in partial saltwater.  They need more salt when they get older.  They have little "beaks"  and very sharp teeth.  We had a Green Spotted Puffer and fed him live food once.  He didn't eat his food whole, like an Oscar, he preferred to nibble.  I am glad you are giving your goldfish a new home, but I recommend he stay the only tenant.  Goldfish need a minimum of 20g.  Please read about cycling your tank.  It's a process of building up beneficial bacteria in your new fish tank.http://www.cichlid-forum.com/articles/fishless_cycling.php
I hope this helps :)