Subbu and myself were constantly exchanging talks on IM about that _perfect_ theme for Windows. A couple of days later, I think I found my perfect theme (although he still wants something non-Ubuntu-ish).
Here’s how my Windows XP looks like:
What I used:
Other than the fact that I’m obviously running on Windows XP Service Pack 2, I used:
- Human for Windows by ~FioreSSj [direct download link]
- Object Dock Freeware by StarDock [download link]
- I also used Tango theme for WinRar to give that complete Ubuntu effect [direct download link]
What you need to do:
Everything else after downloading the required software is fairly simple. Extract the theme files to C:\Windows\Resources\Themes\ and change the theme via desktop Properties -> Appearance. Install Object Dock and set it up to your liking.
To get the taskbar at the top, just right-click on it, uncheck the Lock the Taskbar option, and then drag the taskbar to the top of your screen. Lock it again if you like.
You could further make your Windows look like Ubuntu by using the Human Firefox 2.0.4 theme, Tango Patcher icons (edit: my Avast AV detected it as a virus), and the Human Opera 9 theme by charraoalegria. If you want to take it even further, go get Ubuntu and run it just like we all do. 
However, the music directory in the background is not available for download, atleast by me. 
“How my achievements mock me!” – William Shakespeare
What I was about to comment in your Flickr photo –> ” rocket dock freeware? You mean awn?” THEN it hit me this _is_ a WIndows desktop