My shared networking is working fine with 10.4.9 (3188, XP Pro SP 2, MacBook Pro Core 2 Duo).
You are much more experienced than I am but I assume you tried shutting down (not suspending) the VM, repairing Disk Permissions, emptying caches, then restarting OS X? (When performing a system upgrade I also boot from an external FW drive and run Repair Disk in Disk Utility.)
Also, just curious--did you use Software Update or run the combo updater? (I ran the combo.)
Last edited: Mar 14, 2007