In the past I have written about the fact that Virtual PCs support for wireless network adapters is a bit hit and miss (details here: http://blogs.msdn.com/virtual_pc_guy/archive/2005/10/13/479773.aspx).  As this is a result of hardware limitations the Virtual PC team decided to not enable networking on wireless network adapters in Virtual PC 2007, by default. 

To enable this on a Windows XP system you’ll need to:

1. Open the Start menu and click on Control Panel.
2. Click on Network and Internet Connections and then Network Connections.
   
   If you are using classic mode you just need to double click on Network Connections.
   
   
3. Locate your wireless network adapter, right click on it and select Properties.
4. Check the Virtual Machine Network Services entry and click OK.

On a Windows Vista system you’ll need to:

1. Open the Start menu and click on Control Panel.
2. Click on the Network and Internet and then Network and Sharing Center.
   
   If you are using classic mode you just need to double click on Network and Sharing Center.
   
   
3. Click on Manage network connections, in the task list on the left side of the window.
4. Locate your wireless network adapter, right click on it and select Properties.
   
   You’ll need to approve this action.
   
   
5. Check the Virtual Machine Network Services entry and click OK.

Cheers,
Ben