Post from: http://geekswithblogs.net/thibbard/archive/2005/04/27/38581.aspx
If you need to connect to a Virtual Private Network at windows startup, and you don't want to have the user push connect or enter the password do the following:
1) On the VPN Connect screen, check "Save this user name and password for the following users"
2) Select the "Anyone who uses this computer" radio button
3) Click "Properties" on the VPN Connect screen
4) On the "Options" tab, uncheck: -"Display progress while connecting" -"Prompt for name and password, certificate,etc."
5) In Windows Explorer, browse to C:\Documents and Settings\All Users\Start Menu\Programs\Startup
6) Open a new Windows Explorer and browse to Control Panel\Network Connections
7) Drag the icon of your VPN connection to the Startup folder. This will create a shortcut
Now at Windows startup, the VPN will launch and connect silently.