Perhaps it would be correct to capitalise the 'w', but I was trying to target windows indirectly. I don't want to slap a microsoft feel to it or add tm at the end of Windows. In a way the message is there in a less obvious way.
A lot of people don't see it because I admit I haven't done the best job in conveying it but it's a window inside a grey room. The room is grey because it is a symbol of a closed box, a closed room, a prison in a sense with Linux you open that window. Sort of like the allegory of the cave. Perhaps the ray of light getting in could be Ubuntu based colors, since it still shows the room grey and dull.
Hope that made sense, thanks for the constructive critisim.
I really like it, the typography is very well done, albeit perhaps kerned a bit too close. Also, I think it would be more correct to capitalise the 'w' on 'windows' - referring to the OS, instead of a physical window.
I like the general style. Perhaps the only thing in it's way to being official Ubuntu sanctioned artwork, is it's lack of Ubuntu palette besides the logo. Perhaps the gray background could be replaced by either orange or browish tints.
Overall, a very good wallpaper and design! I like it a lot!