i might suggest toning down the yellow that is there from the original image. it looks like you upped the contrast in the grassy area, but maybe try to get the yellow a little more subtle, like it is in the sunset-ish clouds on the left.
i think the tree could be a little more bold (
http://www.deviantart.com/deviation/19622124/ this might help, if you're interested...)
im also thinkin the purple would look better if it was more blue, maybe make the current blues into a deeper, darker blue to match the dark green in the grassy area (nice contrast in that area though).
uuuuuuuh, that was all visual stuff though. my brain hurts too much to think.
oh, and, is that the proper size for a cd cover? i thought they were square.