If you simply change your name, you keep your post count.
However, ALL your old posts show the new name, so you have the option of keeping the old and having everything change or removing privileges from the old account and re-registering under a new name and really making a fresh start.
Whatever you decide, drop email to any of the administrators (that's me, CKDextHavn, or Lynn, though I seem to do most of 'em and that's fine with me) and tell us what you want to do.
your humble TubaDiva
The Straight Dope