To effectively remove a virus, you'll need a solid anti-virus product such as Norton AntiVirus or AntiVirus Guard. These are popular, proven products that are updated regularly to help combat the past and latest threats.
Once you have your anti-virus software, always ensure that your virus database is up-to-date before starting. Once updated, select 'Scan Hard-drive' and let the scan complete. If any viruses have been found, your software should provide instructions for removal. Remeber, prevention is better than a cure!