On Windows, when I (re-)configure PC for friends and family, I install AVG Antivir for them. It's free, and I've pretty good experiences with it. That is: it runs and updates quite smoothly.

For Linux I've found that they're one of the few with a free product for linux. There's also Clam, but I've not tried that one.

You can download the Antivir product from their site. But I've found that installing it from Yast2 is more convenient, installing also menu-items and so on.

In Yast2 search for 'antivir' and check:

• antivir
• antivir-avguard
  
• antivir-gui

If you check antivir-avguard, the others are checked as well. Make sure that Yast2 also suggest to install the Dazuko packages as well (it will if you check antivir-avguard).

After installation, there are two things left to do.

Enabling AVGuard
The avguard is not started right away. Following this post, you have to edit the file /etc/avguard.conf so that it ends like:

# Enable and configure GUI support
GuiSupport yes
GuiCAFile /usr/lib/AntiVir/gui/cert/cacert.pem
GuiCertFile /usr/lib/AntiVir/gui/cert/server.pem
GuiCertPass antivir_default

Refreshing License file
The updater complaints of an expired key. So following this post, you have to download a new license file from here.
Then remove or backup the old one and replace it with the new one:

• cd /usr/lib/Antivir
• mkdir bck
• mv hbedv.key bck
• cp /home/makker/Zarchief/hbedv.key .
  

Then the updater should work.