If you want to install Oracle, that great big beast, the computer you intend to install must have a static IP address. However for many people their IP address is dynamic, that is it comes from a DHCP server. To get around this restriction you can install the Microsoft Loopback Adapter which creates a virtual static IP.
To install the Microsoft Loopback Adapter follow these instructions. You should be able to start the Add Hardware Wizard by selecting Add Hardware in the Control Panel. In Windows XP if you cannot find Add Hardware in the Control Panel then you can start the Add Hardware Wizard by selecting Printers and Other Hardware in the Control Panel. You should see an Add Hardware entry on the top of the left column.
After installing the Microsoft Loopback Adapter go to the Control Panel, select Network and Internet Connections and then Network Connections. Select the Local Area Connection that is a Microsoft Loopback Adapter (usually Local Area Connection 2). Select the Internet Protocol (TCP/IP in Windows XP, TCP/IPv4 in Windows Vista) and then press the Properties button. Next select Use the following IP address and enter an IP address that should not conflict with your LAN. I use 192.168.1.200 and set the Subnet Mask to 255.255.255.0.
After you set the IP address you can use the Windows host file to assign a friendly address to this IP address. For example add this entry to C:\WINDOWS\system32\drivers\etc\hosts.