Just installed antivirus software for ubuntu: Avast, was very easy, after downloading the .db (rpm is also available):

sudo dpkg -i avast4workstation_1.0.8-2_i386.deb
cd /usr/lib/avast4workstation/share/avast/desktop
sudo ./install-desktop-entries.sh install

… and copy-paste the key which you will get after quick registration process. It works!