I recently tried Trend PC-cillin and I must admit I was impressed.

They have a free online virus scan that they call “Housecall”

Just visit their site at: http://housecall.antivirus.com/housecall/start_pcc .asp and select your country.
Then press “Scan Now” and your computer is scanned completely and thoroughly for all those unwanted viruses.

The length of time for the scan would depend on the amount of files your computer has, naturally, but mine took about twenty minutes.

Any virus detected is automatically cleaned and if it cannot be cleaned it gives you a full explaination of exactly what you must do to clean it yourself.

They also give you the full history on each virus detected and the risk level and files that are usually affected by the particular virus.

I have tried other free scans previously but this one beats them all simply because it is so simple to use and works every time.

They also send you free monthly updates by e-mail, containing useful information about new viruses, virus hoaxes and other important information.

Thumbs up from me.