I know of no way in which to change your name. To register under a different name you will also have to use a different email address, many are available free from various websites.
As a side note I don't think that it really matters if you keep your number of posts or not. It is just a number, if your posts make sense, then you will be respected.
We should all take ourselves seriously...and then crumple that image up and toss it out the window.