You can now get a feel of Ubuntu on your Windows 7 desktop with fan made Faenza and Ubuntu icon packs for Windows 7. These icon packs look really good on Windows 7 and give a native feel specially if you dual boot.
Faenza Icon Pack for Windows 7
Faenza Icon pack installer is made by Mr Ragnarok that will also change startup sounds and orb. It is highly recommended to make backup before installing this. Easy installation and backup instructions tucked inside the package.
Get it from here
Ubuntu 10.10 Icon Set for Windows 7
The icon pack is made by JokerneB. The installer will create a restore point in case you want to revert back.
Check out the video:
Grab the installer from here
P.S. I don't use Windows 7 so I haven't tested them. Also follow the instructions for backup so that you can revert back to default icon set.