BleepingComputer.com: Ethernet from PC to 360 Help

My xbox 360 is right next to my PC upstairs in my room. The wireless router is downstairs and there is no way for me to run ethernet from my xbox to the router so it seemed like my only option was the xbox 360 wireless adapter for 100 dollars.

After looking around I found out that I can connect my 360 to my PC via ethernet cable and in a way, use my PC as the wireless adapter. After I set it up, the xbox detected the wiring and passed the wired network test and the computer would detect a LAN when I powered on my 360.

The problem is that on the console, I fail the IP tests and my computer says the LAN has little to no connectivity because "The Network Didn't Assign A Network Address." There are people who have done this successfully but I can't seem to get it to work for me.

I'm not very network savvy so could somebody please walk me through how to do this.

This guide shows how to do it on Vista but it would be the same on XP. The guide mentions it but just in passing. I would reboot my entire network. Unplug the modem, router, shut the PC down and the Xbox. Then starting at the modem turn them all back on letting the modem's lights settle before the router is turned on, let the router lights settle before the PC is turned on and let the PC boot fully, check that it can surf, before trying the Xbox. Good Luck =)