Looks vary good, the bg fits so well that if your render didn't have hair you would be able to tell almost he bg from the render :P.
You should save it as .gif, while in this sig it gives a good classic look for it looks like a cover of an anime book that was scanned. gifs always make your image pixelated so I wouldn't use them unless you have to.
Your text could actually probably work in this sig, just get rid of the drop shadow, lighten it up a bit and stick a border on it. Well a darker border :P like a dark redish orange.
