Stop my HTPC changing IP address all the time?

[nightrider1470]

I have a router in my lounge and a switch box in my bedroom with a few devices connected to the switch box

Any way I notice that my HTPC keeps changing IP address . well the last number from the address does.. Its a nightmare as I have remote controls which I need to keep updating to work (using my phone)

Is there a way to force a standard IP address ?

Thanks

 

[nightrider1470]

I am on Windows 7 64

How would one go about giving it a static IP address?