you're getting there...definately!
To re-create the forum's background, you'll have to "tile" the background image until you have filled an area that's the size of your sig. Otherwise, to take the little background tile and stretch it to fit, it becomes distorted, much like what you have going on...
As far as the font, I like it although the color of the letters is getting lost in the recon photo. Perhaps try a color that's close to the cloud-gray of the P-38's or maybe an olive drab...something that'll seperate it from the image it's "floating" over.
As far as using a .PNG file for transparencies, you may have some success, but keep in mind that a good number of browsers don't recognize the .PNG transparency and will use the image file's BGcolor as the default. A .GIF is the standard for all browsers and image transparencies, but a .GIF file can only show limited amounts of colors, so you lose alot of quality as a result.
The workaround to this, is to create the illusion that your image has transparency, such as shadows falling across the forum BG. As an example, look up to post #17 where Marcel posted one of his earlier sigs. It is a great example of this illusion!
Here's a couple examples that show the difference between a .GIF with shadowing, and a .JPG with shadowing...the .GIF is transparent, the .JPG is using the forum BG...