The more hardware you can turn off and the fewer applications you run, the less power you'll use. Disconnect any peripherals you're not using and eject PC cards, CDs, DVDs and memory cards as soon as you're finished with them. Wi-Fi and Bluetooth radios use power even if you're not connected to a network or devices, so turn them off whenever you're not using them. If you have a power utility supplied by the manufacturer, you may even be able to disable the wireless card, radio and Ethernet port as well.

You can also disable your modem, serial ports like USB and even your optical drive from Device Manager, but it does take time to go in and turn everything off, and more time to turn them on again when you connect to the grid. If you plan to do this frequently, set up a Windows hardware profile (on the Hardware tab of the System Properties control panel). You can also lower the screen resolution and decrease its colour depth to reduce the workload on the graphics controller, but at that point you need to balance out getting better battery life against reducing the performance of your system so much that it's no longer useful.

Of course, running fewer applications reduces the amount of work that the CPU does; this in turn reduces the amount of power it needs (and also makes a slower processor speed less irritating). Turn off animated and fade effects under Effects on the Settings tab in the Display control panel. Close applications you're not using, turn off features like background spellchecking and disable services you don't need. Rather than closing them by hand, create a batch file using the NET STOP command to turn off services, and TASKKILL /F /T /IM to close applications. Use utilities like Process Explorer and Autoruns (from sysinternals.com) to identify the processes shown in the Task Manager.