Set Up For Small Office Mac Mini Server To Work With Window

Hi There, I am looking someone who can set up a small travel agent office' Mac Mini Server and with 4 windows operating system work stations. The following is what I would like my Apple mac mini server to work with windows operating systems. - File Sharing - Networking - Internet Sharing - Parental Control (for agents PCs) - Restrictions - Active Directory(???) - Security - one of the main concerns / What is the best firewall/anti-virus should I deploy - Domain/Client setup - other things that I should know - What router/switch/hub to buy I am based in Harrow, Middlesex... So I will be looking someone who's local or able travel to come to my office to do the set up... Happy Biding.