that vista wallpaper you're using isn't quite bad, you could use it as an option in your skin. but i wouldn't make it the main "idea"
i also read that you don't know which pictures you could use for the skin instead of that one, so i just googled a little bit and found those:
http://www.hongkiat.com/blog/wp-content/uploads/w...kupuri/vista01.png
http://www.addspice2life.com/wallpapers/windows-v...-wallpaper-106.jpg
http://img.wallpaperstock.net:81/black-&-red-vist..._8708_1024x768.jpg
i don't know if these are just some stanard vista wallpaper, cause i actually use XP, but i do hope they could help you, cause i'm still waiting for that skin!
/ 
