go Start then Run in XP - (Windows key plus R in Vista and Windows 7), then type in the following, including all the spaces:- cmd /k ipconfig /all -- then press Enter and from the black form that shows up, take a note of the numeric code beside the word "gateway" -- usually something like 192.168.1.1. Type exit to close the black form.
then connect a computer to the WRT54G and log in
setup the wireless security(WPA2 mode is preferred)
disable DHCP and change the LAN IP to match the Gateway IP but ending in 253.
finally connect one of the four LAN ports of the WRT54G to your E3000.