You will need a flash USB drive that is 256MB or larger. This might be your first choice since the Acer One does not ship with a CD-ROM drive. One way to install Debian on the Acer Aspire One is to use a flash USB drive. There is additional information on installation of necessary drivers and other optimizations. This page is designed to help with installation of Debian GNU/Linux on the Acer Aspire One Netbook. (it is likely this will improve in later Debian releases) the 11 inch screen models (AO751h) are partially supported in lenny: the wired driver works and can be used for the installation although the installation will give you a working laptop, however many changes will be needed to get all hardware working (including the maximum 1366 x 768 resolution which is not supported by the lenny x.org).
Note that there are several versions of the Acer Aspire One:
