default USB drive installation

Hi all,
I want to make an installer which will install a program in the USB drive (default drive). How can NSIS knows whether there is a USB drive attached and the letter of the drive? Is it possible to do that?
unplug

If you know how to do that using Windows API, you can use the System plug-in to call that API or write your own plug-in. To write a plug-in, download the source code for NSIS and take a look at the Contrib folder, especially ExDLL.