Want a free antivirus that is GOOD?

You could try Avira Antivirus or Avast. I recommend Avast. Go to http://www.avast.com/en-eu/free-antivirus-download
And here is the link for the free licence: http://www.avast.com/en-eu/registration-free-antivirus.php
You will have a licence for a year.
If you need further assistance leave a comment.

you need a virus scanner on the PC You usually goto start> Programs> and then look for the installed program - as mentioned below - run it and there you will an option to scan
Not sure what you may already have, PCs are often supplied with a commercial product such as Norton, Mcaffee or Kaspersky Usually the virus definitons get updated for the first 90days and then you have to purchase the product updates for an annual fee
Check to see what program you have - if is out ofdate, you will need to

1. update and subscribe to the program or
2. remove the program and install one of the free versions avaibable

There is also a good online virus scanner Heres is a link to one of the online scanners http://housecall.trendmicro.com/uk/
If you want to use one of the free programs - I suggest avast, I use that on all friends and family machines - but there are others

1. Avast -- http://www.avast.com/en-gb/free-antivirus-download - to download the file -- Feee Registration for an annual key -- http://www.avast.com/en-gb/registration-free-antivirus.php
2. AntiVir http://www.free-av.com/
3. http://www.filehippo.com/download_antivir/
4. AVG http://free.avg.com/gb-en/homepage

Two other programs to have

1. Malwarebytes http://www.malwarebytes.org/mbam.php and
2. superantispyware http://www.superantispyware.com/download.html

Do NOT have two antivirus programs installed and running onthe PC at the same time To remove the antivirus installed demo installed on the PC - you may need to use one of the removal tools

• Norton Removal Toolhttp://service1.symantec.com/Support/tsgeninfo.nsf/docid/2005033108162039

• Kaspersky Removal Tool A link to Kaspersky - this varies with different versions
• http://support.kaspersky.com/faq/?qid=208279463
• http://support.kaspersky.com/faq/?qid=193239279

• If this solutions solves you problem, please do not forget to rate my solution.
• If not, then please comment back so I can help some more

If you are using Microsoft's operating system, then it will be best if you go by Microsoft's own free security product. You can download free antivirus from the link given below:
http://www.microsoft.com/security_essentials/
Microsoft Security Essentials has been reviewed as better than most of other free antivirus software. All you need is a genuine windows operating system.
Cheers!