If you have a laptop, you can use the efficiency calculator to get Windows 7 to generate loads of useful information about its power consumption. Used in the right way, this can help you make huge gains in terms of battery life and performance. To do this you must open a command prompt as an administrator by typing 'cmd' in Start Search, and when the cmd icon appears, right-click it and choose Run as administrator.

Then at the command line, just type in 'powercfg -energy' (without quotes) and hit Return, and Windows 7 will scan your system looking for ways to improve power efficiency. It will then publish the results in an HTML file, usually in the System32 folder. Just follow the path it gives you to find your report.