Security Software for Business

I have a business with 22 locations. These locations are not networked and are basically stand alone units. I want to buy some security software (leaning toward AVG or Avast Business) but I would like to do remote installation, administration of security patches and monitoring.

So my question is, how can I accomplish this? Do I need to buy a server to install in my house and set up VPN Connections at each location to my server in order to push out the installation and security patches OR, do I need to setup a full network (Active Directory via Small Business 2008 Server) and buy routers etc to establish a true network?

Any help would be greatly appreciated.