I recommend (and use) AVG Antivirus and am a registered partner with AVG.
Their range extends from a free version, to centrally managed and monitored business products suitable for large enterprise deployments (and smaller businesses).
AVG Cloudcare is a particularly good product for small businesses and some home users. It is a monthly subscription service and so avoids the large costs associated with annual renewals of other products, however because it is so low cost I have a minimum level that I can bill on a monthly basis (the actual number of machines depends on the products selected).
For businesses it provides a central point of management so that the settings and status can be monitored through a web based portal without the dedicated server that many 'enterprise' products require. Deployments can be managed by the partner or by administrators from the business.
For home and business users alike the content filter facility is of particular interest as it restricts access to 'unsuitable' sites - a number of categories are predefined and can be blocked or allowed on an individual basis. Additional sites can be explicitly blocked or allowed if necessary.
An online backup facility can also be included within the subscription which provides automatic daily backups of user files into a remote storage facility, every revision to a file is stored so backed up copies of older versions and deleted files can be recovered.