Is it an active dispute or is it something old that just has a comment to the effect of "Consumer disputes account information" and maybe "meets FCRA guidelines." If it's an old dispute that just has that notation, there shouldn't be any difference in the score.
If it is a recent, active dispute, it may affect your credit score because disputed accounts are ignored for scoring purposes. So if you dispute an account with late payments, your score can go up, but once the dispute is concluded and the lates are factored in again (assuming the dispute doesn't get the lates removed), the score drops again. I seem to remember that not all aspects of the account are ignored during a dispute. So, for example, perhaps it still counts for your AAoA even though the lates are being ignored. Someone please correct me on that if wrong.
So, summing up, I think the answer is that if it is a closed dispute, no change. If it is an active dispute, probably no change if there's nothing negative on the account, but possible change if there are negative entries that are being ignored which will then factor back in once the dispute is removed.
Edited for (some?) clarity.
Starting Score: ~500 (12/01/2008)