You can change the language and stay on Windows 7 Starter through a hack, or, you can upgrade to a higher version of Windows 7 if you want, such as Home Premium.
Although to be honest, I would install a Linux OS such as Ubuntu on your netbook. Windows will run quite slow as you're running on an Atom 1-core on 1.6GHz, and 1GB of RAM. This is what I've experienced after using numerous amounts of netbooks.