If you want to recover your Acer Aspire One netbook to its default state, Acer uploaded a disc image on its FTP server from the default Linpus Linux installation.
Acer also published several source codes on its FTP Server.
The disc image can be burned to a DVD, or can be installed onto a USB stick, if you don't have an external DVD drive that can be used to install the software on your Aspire One.
On the Blog of macles* you can find a tutorial about intalling this image (also with an USB stick) This is a Unetbootin modification. It basically mimics the installation procedure used on the Recovery DVD and prepares the USB stick without ever having to burn or boot a DVD.
You can download the disc image here. [link updated 12-12-2011]