Hi there,
You can do this with several skins or themes available. My personal recommendation is to go and get WindowBlinds from
www.stardock.com. I use this program and it not only allows you to change the look of your computer, it also allows you to customize several other settings such as setting a specific window to stay on top, or to minimize windows to the system tray. Once you've got WindowBlinds, go to
www.wincustomize.com to find additional themes.
I used to use the msstyles themes that you can find at ThemeXP, but recently, I've found that their site to be littered with ads and spyware.
Hope this helps.