This is very nice. I am not sure that I like the purple background (and my favorite color is purple, lol!) But it's just a bit too unrealistic a color with the tree for me. Maybe a navy background with stars? Was this done in Bryce? I love your idea though.
Nice computer work! maybe the light on the top of the tree is little too bright, I'd like it little more subdued, but that's just a detail.Overall, I like it.
I believe a soft blue background would have been better on this. The light on the top of the tree is too bright. Takes away from the photo I believe.You can't really tell if it's the sun or an ornament on top of the tree giving off this light. Sorry :(