What you're wanting to do is commonly called "reformatting". Bascially, you're formatting your hard drive(which erases existing data) and then doing a fresh install of your OS.
All you do is put in your OS install disc, format your hard drive, install windows. After Windows installs, you'll need to download the drivers from your netbook's manufacturer's website. Just google reinstall windows if you need more help.
Imaging is basically taking a complete snapshot of everything on your computer and copying it to a file that can be used to deploy to however many computers desired. This is mostly only used for schools/businesses. Say I work at a school and I buy 100 new computers. I can either install all the necessary software manually on all 100 computers, or I can install it on it on 1 computer. Making sure everything is set up exactly how I want, then I create an image using that machine. I can then image all 100 computers(probably not all at once). Doing this saves A LOT of time. It's also handy for if a computer has software issues, often it is easier to just re-image the machine, which reverts it back to that snapshot when everything worked right.
Ghost is a common imaging software. But as I've explained, you don't need ghost at all. Pretty sure you have to pay for Ghost, although there is FOG(Free Open-source Ghost).