Most of them loves ubuntu because of the look and design, if you want to feel the same need to install it, but that may take time to install it, but if would like to feel it instantly you can download the themes for windows. Here is the some collection of ubuntu themes for windows.
1. Ubuntu Skin Pack.
Download Ubuntu Skin Pack | More Info
2. UbDark for Windows.
3. Ubuntu Ultimate Customization Pack.
4. Ubuntu transformation Pack for Windows XP.
5. Ubuntu Transformation Pack.
Download Transformation Pack | More Info
6. Ubuntu Theme 1 Click Setup.
Ps: Images in this may not have appropriate pixels.we have tried to adjust this, but could not do it.