Yes there is.
Under the wireless settings in your router's setup/config page, there should be an option to disable "SSID Broadcast." This will make the wireless network "invisble." In order for you to cononect a computer to the network after you have disabled the SSID Boradcast, you will need to select the "conenct manually" option in windows and input your networks name and WEP/WPA/whatever security key you may be using in order to successfully join the network.
Hope this helps.