The following link to the CERT coordination center systematically tells you the basics of Home Network Security . Be aware that no anti-virus software can detect all viruses, trojan horses, or worms. Isolate your Internet and Mail directory from your other working area Back up your files on a regular basis. Do not open any files attached to an email from an unknown source. Do not open any files attached to an email even if it appears to come from a dear friend or someone you know.
Some viruses can replicate themselves and spread through email.
Confirm that they really sent it. Delete chain emails and junk email. Do not forward or reply to any to them. Exercise caution when downloading files from the Internet. When in doubt, do not download any files.