Nice job!
You might want to look into a free program called "wintopo" that at least semi-reliably converts graphic images (like scanned-in art or other web graphics jpg's, gif's, etc) into a raster format (DXF). It saves me TONS of time, and although I sometimes have to erase bits of "noise", I typically don't need to do anything at all to it.
Imagine all those little art detail books on your scanner.. full of engraving potential. with celtic knots and all kinds of things... merely a few clicks away.
(works best on line art drawings)