Thats how my sig is, it's transparent background, i can put it on any color and the background color will shine through the shadow. It's actually a really wide sig, I just never cut it right when I saved it, I'm too lazy

As for your site, I kind of like it.
There are a couple problems, I don't really like the background stripes in your header, and the background stripes for the body change position, when going from the home page to any other page, That is distracting and annoying.
I also don't think the shadow on the text in the image with the computer looks right.