well i think i have it now,,i just made a new file and pasted the old in it,and now it looks like it went to transparent!!! I still see a white edge? Could this be because of the drop shadow?
as far as the white goes, I see it in one of your screenshots & not the other, but I would remove it from a layerd version so there is absolutely no white. In my earlier example, & pulled down the gif from your sig & removed the white with the magic wand, so it got fuzzy by the shadow as to what it saw as white... still looked ok, but on yours you did a few other things I question.
Your current sig has a larger shadow, that doesn't add anything IMO... and then it is cut off with a sharp line which ruins the effect entirely. You also have a bigger logo, which might be fine for your website, but for a signature that shows up a dozen times in some threads... you might consider cutting back on that a bit
..not trying to run you around... just sharing an opinion, and getting some receptivity to it... I keep sharing
I got your email, & the .psd file with no white in it looked like a 3 or 4 click "save as" operation to get what I would expect to work, so lets see...