Kia-kit,
Just a small tips on currency conversion, just in case you withdraw too much poland currency or any other Eastern country currency:
#1 when you have euro and you wanted to change to their currency:
NEVER change in the train station or airport. These currency exchange store knows that you have lot's of Euro and they will take advantage.
So, MUST always change at the bank to get the best rate. (better still get from ATM).
#2 when you're leaving the country and you wanted to change back to Euro:
Now, you can change at the train station or airport or the bank. The rates are similiar.
BTW, for the ATM, there is a withdrawal limit similiar to singapore, each time is S$1000 and each day is S$2000.