Antivirus
https://help.ubuntu.com/community/AntivirusIf you read the webpage above, however, it may make you feel better about the security of Linux: virus infections are not impossible, but they're much less likely than in Windows
Here's the ClamAV website:
http://www.clamav.net/lang/en/download/packages/packages-linux/Try this to install it:
Applications >> Accessories, click Terminal'
When the terminal comes up type
sudo apt-get install clamav clamtkPress return
(Generally you'll be asked for your root password; I don't know what happens with the liveCD)
You'll be asked if you want to install certain packages: type
y and press return
when it's done installing, close the terminal window
What is
sudo apt-get install clamav clamtk?
sudo means you want to run as root
apt-get handles packages
install is what you want apt-get to do
clamav is the antivirus program
clamtk is a graphical user interface (GUI) for clamav so you don't have to work in terminal
You can find the antivirus now in Applications >> Accessories (I think)
You may have to update clam to get the virus definition files
IIRC you have to be proactive using clam: it doesn't update itself; you have to update it, and make sure regularly that you have current anti-virus files. Also it does do much except tell you that a file is infected: you're responsible for deciding what to do with the infected file, and I don't think clam will try to repair it or quarantine it
Given the problems you've had, you might also want to look into firewalls. See ufw here:
https://help.ubuntu.com/community/UFW