Netbooks' sole purpose is to be cheap, light weight and easy to use on the go. Without a long lasting battery there is no use for such a device. Fortunately there are a few easy steps you can take to ensure the wireless productivity stays as long as it's intended by the factory.
Most netbooks come with a 6 cell battery now and with most common parts involved they're good for about 6-10 hours depending on the graphics chip and processor used. N270 uses more power than an N450, but computers' battery performance installed with either can be lengthened.
1. Check the brightness setting of the screen. There are situations where you need to use a brighter value but in most cases you can get by with one notch above minimum once your eyes are used to it. Between minimum and maximum values there is a 60-120 minutes difference, so when you're in a not so well-lit room take the time and lower screen brightness a little.
2. Shoot down programs you don't use anymore or don't even know about. Start the task manager and find hidden tasks that use the processor. There is a tenfold increase in processor power consumption between idle and load states. There are instant messaging clients, browsers and all kinds of applications that keep a secret thread up and running even if there is no other sign of the program on the taskbar.
3. Switch communication ports you don't need off. If you don't need to get online or there is no wireless network available where you're using your mini notebook computer, you don't need your wi-fi adapter. It adds to consumption considerably, switching it off can add up to an hour to the final figure. The same goes for 3g, Bluetooth, Infrared ports and USB peripherals too.
4. Use sleep mode extensively. Now that hardware and software finally works together there is no reason not to set the laptop to go to this state when you close the lid. Some minis are already set to this behavior by default but you can check for yourself under Power in Screen Savers tab after Right Click -> Properties on the desktop.
You can shut your mini notebook down and restart it every time you close the lid but putting it to sleep and waking it up takes about 15 seconds total, and while it's dozing off it uses minimal battery. You can easily get away with keeping it so for days at a time.