To set the default printer in the registry, follow these steps:
- Start Registry Editor (Regedt32.exe).
- Locate and click the following registry key:HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
- Click the following value:Device=Printer1,winspool,LPT1:
- On the Edit menu, click Modify, replace the first value (Printer1) with the name of the printer that you want to set as default, and then click OK.
- Quit Registry Editor.
Source: http://support.microsoft.com/default.aspx?scid=kb%3ben-us%3b271257