I'm throwing in the towel too at this point. I've uninstalled and reinstalled multiple times and tonight I pulled the pin header and used the wired install - no dice. I also multimetered the FCC cable and I believe it's okay. I've tried multiple computers connected directly port to port. Maybe during all the screwing around and multiple installs I damaged one of the LPC holes. Who knows. Regardless this has used up way too much time. What should have taken a couple hours has taken over 20 and still no luck. I've done everything that can be done, read every tutorial, faq, thread and suggestion on every xbox board. Hell, I can pull the motherboard like a pro now.
Too much to troubleshoot: FCC cable, parrel settings in XP, actual soldering, remote possibility of a bad chip. Hell the only thing I know for sure is that D0 is correctly wired and that's supposed to be the hard part. If it even had Cromwell on it I would at least be able to narrow it down.
Got to know when to cut your losses. This puppy is going back and at this point I'm not sure I want to try another.