Someone please help with my sig's transparency

http://img3.imageshack.us/img3/5522/vita1zsig1.png

that is the image's direct link on imageshack. under this post, the sig I have is the sig I want, but it doesn't have transparency as it used to. I had to resize the signature and when I did, it had a white background. please someone help me get its transparency back.

Thanks