Outer glow on characters is generally not a good idea. It separates them too much from the background, and in a scenic you really want the character and background to feel as one single piece. Also, try smoothing out the extraction a little: an eraser with a soft edge will get rid of the jaggies pretty nicely. The background also could use some work. The problem with using screenshots is that they don't size up very well, unless you're willing to spend a lot of time re-cging it. I would try using a stock photograph of tree and sky, a photograph that's at least as large as your canvas, so you don't have any resizing artifacts, and painting over the photo to give it a more stylized anime feel.

I like the simple scenery for the background, it really suits the scan. I also like the clarity of everything. Good job :)

As Tama pointed out, the glow around the girl makes her stick out a bit too much ^^;; The background is rather blurred, which would be ok if there weren't such different clouds in the sky. The ones on the bottom right have a nice painted look, but the ones on the top left look rather odd and messy. Jaggies are a bit of a problem, but apart from that this is a pretty nice scenic wallpaper *^.~*