Ideally, you would have gotten the OC to pull back the collection when they agreed to accept your payment. If you didn't then, ask them to do so now.
Medical collections are unique in that they don't arise from your seeking credit. In fact, much of the time they result from the OC screwing up the billing, or not trying to work something out with you.
* 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