I found a solution.
So, if you are a proud owner of the Aspire One D257 with Intel Centrino Wireless-N 1000 on board you better stick to Debian testing (codename «Wheezy» at the moment). After the installation (netinstall from a usb stick is the best choice) you need the next packages, apt-get them:
firmware-linux firmware-linux-free firmware-linux-nonfree (for general firmware support)
firmware-iwlwifi wireless-tools (for the wifi network card mentioned above)
firmware-realtek (for better support of the Realtek network adapter)
Everything now works just perfect.