Hey, they look really good :) What you need to do is use the transparency in the original image. The format exported from the dump is .tga and the saved format is .png. TGA saves transparency in alpha channels, but to have transparent PNG you need to create a layer with alpha. (I'm assuming you're loading it up in Photoshop, other programs should be similar though.) What I do is I bring up the Channels palette (Window->Channels) and ctrl+click the alpha channel to select it. You can then copy all layers (Edit->Copy Merged) and paste to a new layer, then hide all the other layers. What you've got is a single layer with the right colours and transparency, and you can now just save as PNG.