Check out this web page:
http://www.daybarr.com/blog/2007/05/11/how-to-change-ip-address-from-the-windows-command-lineIt explains how to use comand prompt to change your ip address, gateway and dns servers plus how to chage it back to dhcp again. It uses netsh.
This is how you set your ip address, subnet mask and gateway:
netsh interface ip set address "Local Area Connection" static 192.168.1.140 255.255.255.0 192.168.1.1 1
netsh interface ip set dns "Local Area Connection" static 4.2.2.2 primary
Then back to DHCP
netsh interface ip set address "Local Area Connection" dhcp
netsh interface ip set dns "Local Area Connection" dhcp
This is so helpful. You just put this code in to a text file and change the extension from txt to cmd. Then you can open it and it will set your ip address. Then have another file that will change it back to DHCP again.