Oddly, you will have better scores if at least one card reports a balance (under 10%) than if they all report $0. TU especially loves this, and I just got a 14-point jump for doing this. One card reported $7 --that was fun!
Aim for having fewer than half of your cards reporting a balance. And for anyone new reading this, realize the importance of timing your payments so that YOU control what is reported to the CRA's.
Depending on what baddies you have on your reports, improving your util is the fastest way to raise your scores, and you're completely in control. (As long as you can get the CCC's to report, and the CRA's to post, your new balances, that is!

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* Credit is a wonderful servant, but a terrible master. * Who's the boss --you or your credit?
FICO's: EQ 781 - TU 793 - EX 779 (from PSECU) - Done credit hunting; having fun with credit gardening. - EQ 590 on 5/14/2007