If you Prune posts...rather than deleting them..the post counts will remain the same
On my forum, I move all posts that need to be pruned..to a separate forum, just because it's easier. But you can prune selectively as well
Then you can prune the posts selectively..I only mentioned that I put them in a separate forum, because we sometimes prune quite a few. But you can do them one by one. Pruning does not affect post count...Deleting does
I see everyone giving this guy a hard time, but this could be done in vB2 where after deleting posts, the user's post count decreases. Someone created a hack which prevented this forum happening ... For you's who asked "Why Delete??" ... there's a few good reason, but one that really comes to mind is some of us run huge forums and there's no reason to keep dead or resolved posts around because the forum a very active and keeping them around is NOT a good forum performance maneuver.