If you are looking for the solution for your Virtual PC 2007, see here. Here, I'll show you how I hack Windows 7 to make this work in wireless network.
- Create and start wireless hosted network in Windows 7. See the detail here.
- Enable (host) wireless adapter to allow ICS for MS Virtual WiFi Miniport Adapter. See the detail here if it is disable by network administrator.
- At your Virtual PC, Set "Networking Adapter" to use "Microsoft Virtual WiFi Miniport Adapter".