Four options are affordable for enterprise-grade security inside a small office: This article, which I wrote for Mobile Pipeline, addresses the four servers and services that have a price and focus square on the small business of 5 to 100 users. Above that range, and you really better have an IT department and integrate your directory services. But for a few dollars per user period (in house) or per month (hosted), a small business can have a level of Wi-Fi link security that approaches that of a large enterprise.