When you dispute an account, other than a collection or pubic record, it is not used in calculating your score. If the derog was recent, your scores can take an immediate (and temporary) hop.
Don't fall too in love with the new scores --if the derog is not removed, they'll go right back where they were.
* 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