Image > Canvas size, and change it to something more suitable....
Also your signature is just gobbled tags
I tried that it makes the picture dissapear, and what you mean ;o
ctrl m to merge all the layers to one then change the canvas size to a good size. Then move the image to where it fits best.
Also your signature just shows text and not the actual image like this
[img width=1000height=150]http://i43.tinypic.com/29momiq.jpg[/img]