If you are up for a big challenge, you may configure your Windows 2008 Server as a Domain Controller, AD will be created automatically. It is always a good practice to configure DHCP and don't forget the DNS from the Server, then you may create/add all 10 Users in AD Users & Computers - see Lemur's Post on how to join a computer in your Domain Controller.
If you decide not to configure DHCP in your Server, you may enable DHCP from your Router (it will create conflict if your have both enabled). Make sure that all your 10 PC's have DHCP or Auto IP Enabled, they will have to receive the IP Addresses from your Router or Server. You will get the IPIPA Addressing if the IP is not configured properly from your network.
If this is the first time that you are setting up a Domain Network, you will need to do a lot of reading and training. A few others will go through some professional In-Person training, I was one of those.
A good Tutorial here
on how to configure a Windows 2008 Server as your first DC.
You don't have to have a Domain Network, Workgroup will also do.
Hope this helps.