I am having the same problem, but rather than ICS having changed from Vista it appears to be W7 system protection that is the issue. The xbox on a direct connection is classed as an 'unknown network' and the ability to change the designation is greyed out.
W7 classifies unknown networks as a threat and wont communicate. I have tried to associate them using both DHCP & fixed address without success

I just tested something and it's odd. I can download stuff off of the marketplace, but I still cannot download patches. The stuff of the marketplace downloads exactly like before. Another thing I found out. When I'm downloading patches, before it says update failed, it actually downloads a little bit of the patch. It would take forever to download the patches this way which is why I want to try to fix it. Hope this helps you guys find a solution.