Here is my setup as an example.
My router is set to 192.168.1.1
My router's subnet mask is set to 255.255.255.0
The starting IP address I have set on my router (This is the IP address that the router starts handing out IP's at) I have set at 192.168.1.100 so basically any device that doesn't have a static IP will start getting assigned IP address' from 192.168.1.100,
then 192.168.1.101 etc.
I then have the static IP address of my Windows Home Server set as 192.168.1.81 basically I can set it at anything between 192.168.1.2, and 192.168.1.99. The only way that my server would conflict with any other device on my network is if another
device is set to use static IP, and happens to have the static IP set to exactly the same address as I set for the WHS box..
So in TCPIP properties I have:
Use the following IP Address:
IP address: 192.168.1.81
Subnet mask: 255.255.255.0
Default Gateway 192.168.1.1
I've also got the DNS server set to use Open DNS
208.67.222.222 & 208.67.220.220
Also I find it odd that you don't have your server connected to the internet, without an internet connection you will never get any of the security updates from microsoft.
Hope that helps.