If you’re a Windows user you need an Anti-Virus. I do not recommend the current top sellers: Norton Anti-virus or McAfee. They’re bloated and less effective than others. Check any anti-virus before you buy by visiting the independent Virus Bulletin. Any anti-virus you choose should also be certified by the ICSA Labs (all the big commercial products are).
Symantec’s Anti-Virus Research Center is a good source of virus information. The site also lists hoaxes and offers many free virus removal tools. Most anti-virus companies maintain similar sites. Unfortunately, there’s no standard for virus names, so you may have to look around to find the right page.
If you are having problems installing an AV product it may be that your system is infected. Use one of these free online anti-virus scans to check for infection:
Currently these online scanners require Internet Explorer, but a cross-platform version of Housecall is reportedly under development.