Windows 7: Change the Settings for Virtual Windows XP (or other Virtual Machines)
Contributed by shamanstears 
May 5, 2009 
Tagged: Microsoft Windows 7
You may want to change the settings for your Virtual XP or other Virtual Machine (such as memory, adding a hard disk, disabling Auto Publish, etc.) that you have on your Windows 7 system. While the method of doing this isn’t easy to find, it is easy to do.
1. Open the desired Virtual Machine, in this case, Virtual Windows XP. (Go to the Start Menu, select All Programs, expand the Windows Virtual PC Directory, and select the desired virtual machine)
2. When the Virtual PC window appears with the desktop of your Virtual Machine, go to the menu, click on Tools and select Settings.
3. You will see all of the settings here, but if you try and make changes, most of them will be ghosted out. Go to the bottom of the left pane and select Close.
4. Go to the right pane and select the Prompt for action radio button.
5. Click the OK button.
6. Click the X in the upper-right corner of the window. You will be prompted for an action, use the dropdown and select Shut Down. Click the OK button.
7. After the Virtual Machine has shutdown, go to your Start Menu.
8. Select All Programs.
9. Expand Windows Virtual PC.
10. Select Virtual Machines.
11. In the resulting Explorer window, right-click on the desired Virtual Machine and select Settings.
12. Use the left pane to select what you want to make changes to and use the right pane to make the desired changes. When finished, click the OK button.
You can now start your Virtual Machine and the desired changes will be in place.