im sure all of you know that xbox 360s are notorious for being difficult to work with macs. so heres my problem:

i have a G5 desktop mac running OSx 10.4.11. its connected to a toshiba router (PCX2200) via airport. what i want to do is connect my Xbox 360 via ethernet to my mac and have it share the airport internet connection. this way i can avoid buying a wireless adapter and still use Xbox Live and if i ever upgrade my airport i won't have to worry about wireless issues either. I've found a couple tutorials. i mainly followed this one here:

Share Your Mac’s Wireless Airport Network Connection With Your XBox 360

it worked the first time around, my Xbox 360 downloaded the new experience update, etc. then a couple days later it refuses to connect and i can't join Xbox Live. my Xbox doesnt even get past the network step in the connection test.

i'm not sure what to do and i would appreciate any help, advice, or tutorials anyone could help me out with. this is highly frustrating especially since it worked once already just fine.