I've run into this problem, too. Ever since Windows NT 3.1, Microsoft has provided the Microsoft Loopback Adapter--though very few people know it exists. It's a software-only network card. Your OS thinks it's a network card so network apps will function but you don't need to have a physical network adapter enabled.
To install this driver, open the Control Panel and run the Add/Remove Hardware applet. At the Welcome screen, click Next. At the Choose a Hardware task screen, make sure Add/Troubleshoot a device is selected and click Next. At the Choose a Hardware Device screen, select Add a New Device and click Next. At the Find New Hardware screen, Select No, I want to select the hardware from a list, and click Next. Select Network Adapters and click Next. Finally we've arrived at the Select Network Adapter screen... we're almost done. (This was much easier before the wizards.) From the Manufacturers list box, select Microsoft. In the Network Adapter list box, select the only option, Microsoft Loopback Adapter. Click Next twice and click Finish.
The new software-only NIC will appear in your network settings already enabled, no reboot necessary. Configure it like any other NIC. If you use a private IP address (like 192.168.13.74), you can leave it enabled all the time and not have to worry about it affecting your other network adapters.
This was first published in April 2001