Your wallpapers are definatley improving, especially the last two. But I do think they suffer from too many effects, If you are going use special effects use only one or two and perhaps also lessen the amount of people in your wallpapers, maybe one only on the right hand side, leaving the left side plain, remember icons will be over the top of these and a simpler less cluttered desktop always looks better. But good work anyway.
One more tip is to use imageshack to upload your images, then use the thumbnail for forums link in your post. This puts a small icon into your post and when it is clicked a new window opens with the image automatically scaled for the viewers screen resolution. It makes it much nicer to view, personally I hate having to use the scroll bars to see big images posted here.