OK, here's how to use netsh to set your interface back to DHCP:
C:\WINNT\system32>netsh interface ip set address local dhcpC:\WINNT\system32>ipconfig
Windows 2000 IP Configuration
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . : IP Address. . . . . . . . . . . . : 192.168.0.19 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : 192.168.0.1
last updated 2013-01-10 20:38:44. served from tektonic.jcomeau.com