Karrie, be glad to help....not entirely sure I understand your problem. XBOX Live doesn't know or care anything about Vista, unless you're using Vista as your connection sharing tool.

When you say "the IP address won't pass," what exactly do you mean? An invalid IP address given to the XBox usually causes the XBox to fuss at you if you specify it...the other thing I wonder is if perhaps your router, if it is handing out addresses automatically, might have handed out an address the XBOX has used previously, but doesn't know it's been reissued to a different device.

Way out in left field, of course, but if you could provide a bit more detail, I could be more helpful.