Download software Virus detection and protection has become very difficult with the ever growing number of PC users. Note that email and the internet is only one way that a virus can spread onto your harddrive. Do not open any files attached to an email from an unknown, suspicious or untrustworthy source. Do not open any files attached to an email unless you know what it is and why it has been sent to you, even if it appears to come from a dear friend or someone you know.
Some viruses can replicate themselves and spread through email.
Better be safe than sorry and confirm that your correspondent really meant to send an attachment. Do not open any files attached to an email if the subject line is questionable or unexpected. Exercise caution when downloading files from the Internet. Ensure that the source is a legitimate and reputable one. If you're uncertain, don't download the file at all or download the file to a floppy and test it with your own anti-virus software.