Interrupting Windows Startup with a Program

[Zuve]

How would I go about interrupting windows login as to launch a security program. I want to write a program that makes it so you use a USB Flash Drive to log in to your account. Any ideas on how to achieve this. It could launch after startup, as long as it intercepted any keystrokes(to avoid Ctrl+Alt+Delete) and launched before someone could gain access to any files. Any tips are appreciated. Thanks!

[Homberto]

Perhaps this could be of any help: http://answers.microsoft.com/en-us/windows/forum/windows_7-desktop/how-to-start-program-before-user-logon-windows-7/2bff97c4-c037-437c-9fa7-b143a3ae5189?auth=1

Also, I know I would lose the flash drive in a day. xD