I think Predator is what you are looking for. It has many features, which will help you.
What I like most of this software is it doesn't completely integrate with Windows system files. I just run as an application. It's light weight. It has an alarm option.
To get most security out of it, I recommend to
- have your Windows account password protected
Always required option for password in Predator. So you have to provide the password and USB to unlock.
- enable to start with Windows option in Predator. It's in Advanced Settings tab of Predator
Write to lowest in Predator. So that it'll activate its lock mechanism as soon as you remove your USB.
What I don't like about this software is even you are locked by this software, you can still shutdown, restart, or switch to other user by typing Ctrl+Alt+Del. Fortunately locked person can't access the Task Manager.
It allows you the option to enter pin on USB insertion in free version.
Doesn't completely integrate means, it doesn't lock your user account upon USB removal. You are still logged in. Your Windows user session is still active. It just makes your screen black and you can't run any application. Ctrl+Alt+Del still works, but you won't see a link to Task Manger in it.
It works as any other start-up application. So USB and PIN doesn't require you to start your computer. After you come to your Desktop screen by entering password for your Windows account (if you have any), Predator will start like any other software in your start-up. At this point, if your USB is not plugged in it'll lock your system (make a complete black screen). So according to your processor speed and number of start-up application it may take some seconds to minute to start the Predator at start-up.