OK - How I got to where I am:
(1) Using Acronis, I imaged my Vista 64 SP1 install to a new/clean partition on a separate drive, and set the system up for dual boot. Verified both work normally.
(2) Upgraded one of the images to Win 1 build 7100, as requested by MSFT in the MSDN blog. No other settings have been sullied with, except as detailed below:
(3) Now: The Vista 64 install is working as it as been: I can see the rest of the computers in the house, access the Internet, etc etc etc...
(4) Win 7: *Very* limited access - I can use Ventrilo (a VOIP program) to reach out on the internet to communicate to other people. So I know the internet is "there". But no browsers or other programs appear to work.
(5) So I tried the obvious and disabled the Firewall completely to see if it was a setting issue. No Joy - Same issue as before
(6) Win 7's troubleshooting says the Internet is there, but that a remote device is refusing the connection. So I called my ISP on the theory that they may have flagged my Win 7 install as not authorized on their network. But no.
(7) A little browsing says there may be an issue with now IPv6 is working, so I disabled that - No Joy. Currently re-enabled.
(8) Enabling and disabling Homegroup has no effect, either.
(9) The Troubleshooting details tell me "Primary DNS Server is not set up to accept connections on port 'Domain'." And the DNS server is not available.
Obviously, something is mis-configured, but for the life of me I haven't been able to figure out what that something is. Hell, It's probably been staring me in the face the whole time...
Screenie of some efforts to Ping: Ping picture by Scotteq - Photobucket