ohhhhhhh my bad, thats insanely helpful and cool thankyou! *hugs* ^_^
So, I put one piggy bank or safe down in one world, and another in the world your playing on and you can move items betwen them?
You don't have to transfer items between them. Think of it like cloud storage. If you play a game on your xbox and put its save file on the cloud, you can now go to your friends house and play the game using your save file without having to transfer them over with a memory stick. Same concept here.
Here is some info from the wiki on the safe:
The Safe is a Storage item with 20 slots to store Items. It functions identically to the Piggy Bank, except that it does not require a wooden platform or furniture, as it can also be placed directly on Blocks. It also costs 20 Gold Coins (as compared to the Piggy Bank at 1 Gold coin), and its Inventory is separate from the Piggy Bank's. It can be bought from the Merchant after Skeletron has been defeated.
The Safe (and Piggy Bank) function similarly to other Storage Items, but with some important differences:
Each Safe contains the same items (when accessed by the same character), no matter where they are placed within the world. Purchasing multiple Safes will not give you more space, but will offer more points of access to your Safe contents.
The Safe can be picked up even when it contains items. This makes it a viable way to expand your character's inventory slots. It can be removed with a Hammer to be picked up again.
The Safe's contents are saved with your character data, instead of the World data. You keep its contents with you from world to world, and from server to server.
The Safe's contents are exclusive to each player, so other players will not have access to items in your Safe. This makes it useful for item security on PvP servers where stealing is allowed.
Multiple players can use the same Safes without having access to each others items. Each player will only see their own items when accessing the same Safes.
Moving coins you gather into a Safe (or Piggy Bank) periodically may be useful, especially when exploring hazardous areas. Coins stored there will not be lost in case of death, even if the Safe is in your character's inventory at the time.