Howtogeek posted a tutorial about tweaking the Low Battery settings on your Windows 7 netbook

If you've got a netbook with really great battery life, you'll probably still have loads of time left even with only 10% of the battery remaining. Here's how to tweak the settings so it alerts you or goes into sleep mode at a more reasonable time.
Note: obviously if you don?t have a great battery in your laptop, you should probably be careful with these settings or you might lose data. If anything, you?d be better off making the notifications happen sooner in that case

  How to Tweak the Low Battery Action On Your Windows 7 Laptop