this has been asked before here, and the answer is no (from what the mods have answered).
But those were people wanting to keep thier post count and history (signup date). As for Sponsorship, I would think that if you signed up for another Username (with a different email, as only one username per email) you could ask to have your new username show the sponsorship logo. But don't quote m on this
Mike is correct. You can't change your name and keep your post count, but you can reregister with a new name and we can transfer the sponsor information. Just send an email to Chrisc@wdwinfo.com and he can handle the details for you.