Paying off or not doesn't matter. What matters is a long track record of timely payments larger than the minimum amount due. The only way to do that is to carry a balance. The CU might view the minimum payments as a negative, even though it's interest free. Make payments at least 2x or 3x the minimum amount due, even on 0% interest cards/loans. Once you've established a credit history, you can use a different strategy to take advantage of 0% rates if you want to.
The other thing you can do at a CU is to sit down face to face with a loan officer and explain your credit situation with them and ask how they can help you establish a credit history faster. It helps if you carry a nice balance in your CU account over a period of time and have some history with them.
-David
[This message has been edited by LIH Prem (edited Dec 15, 2003).]