win2k and above...
Start>Settings>ControlPaneland open network and Dial-up Connections. Right click on the NIC you want to change and click on properties. Under the general tab, hit the configure button, then click on advanced. In the Property section, you see an item called “Network Address” select it. Under “Value”, type in the address you want with out the "-"
Goto command prompt and type in “ipconfig /all” to verify.