Windows has plenty of features that you can turn off to speed things up. Here's how to find the features you don't need.
The features that you can disable here are the easiest ones to turn off - and switching them off is likely to yield the biggest improvements in performance, too.
Aero: Vista, Windows 7
With Vista, Microsoft gave Windows an attractive, transparent look that it dubbed Aero. With Aero on, the headers at the top of each window are slightly transparent. You can't see what's behind them clearly enough to read them, but it gives the desktop a nice, three-dimensional look.
But that look eats clock cycles, and depending on the speed of your PC and your willingness to trade performance for aesthetics, you might want to turn Aero off.
If you're using Vista, right-click the Windows desktop and select Personalize, Window Colour and Appearance. Click the Open classic appearance properties for more colour options link (if you don't see the link, Aero is already off).
In Windows 7, right-click the Windows desktop and select Personalize. Select one of the themes that are displayed under the 'Basic and High Contrast Themes' heading.
The Sidebar: Vista
That bar full of widgets on the right side of the Vista desktop must have seemed like a good idea at the time. Who wouldn't want a feature that distracts you when you need to concentrate, steals precious screen space, and slows system performance like an anvil chained to a swimmer's leg?
Someone must have complained, because Microsoft didn't include the Sidebar in Windows 7.
Unlike the other features in this article, this one has no possible redeeming value. I'm not suggesting that you consider turning this feature off; I'm urging you to turn it off without further consideration.
To remove the Sidebar, Right-click a blank space on the Sidebar and select Properties. Uncheck Start Sidebar when Windows starts.
See also: 33 ways to speed up your PC