To answer your question, "Do we establish an Internet account or sub-contract for an intranet setup?" you should do both. Windows networking has become so easy that anyone could set up a network -- but setting up a network that meets your requirement for security requires an expert. Regarding the hardware and software you'll need, I would recommend setting up a Windows server system. Use Windows Server 2003 Standard Edition, if it's available when you start building your network.
Dig deeper on Microsoft Active Directory Tools and Troubleshooting
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.