if anybody has tried setting up the xdk on XP x64 Edition and found that the shell extensions aren't supported then this might be of interest.
This will give you a shortcut to 'Xbox Neighborhood' that works pretty much as it does on 32bit XP.
1. Install the shell extensions as you normally would.
2. Create a new shortcut on your desktop.
3. For the target location enter
4. Give it the name 'Xbox Neighborhood'
5. To setup the correct icon, hit the change icon button and point it at
6. Select the icon which has the word 'xbox' readable on it.
7. Click OK and all is done.
Seems to work ok for me so far!