Vista is sexy because of its new aero glass transparency effects. Here is how to enable and disable this new eye candy. Found this over at Tech-recipes.com
Eye Candy! The new transparency (or glass effect) in vista is amazing. But it can take a lot of your cpu and gpu cycles to run it on a daily basis.
To Enable or disable this effect:
1. Right-Click on a blank area of desktop
2. Select Personalize from the context menu
3. Click Window Color and Appearance Option

4. Here you can check if you want to Enable Transparency or not.
5. You can also disable the whole aero glass theme from here. Just click the Open classic appearance properties for more color options link.
6. Select a non-Aero theme and click OK.
These effects require pretty heavy video card specs… If you can’t get it working, it might be time to upgrade your system.