It appears that the latest version, 11.5 or 11.1 of the logitech driver for webcams, for Quickcam Communicate STX in particular, would not support taking picture from Windows internal support of webcams (Right clicking on the webcam in my computer to get pictures would give an error message: Unable to take picture), eventhough it works well with Quickcam's own software. In fact, someone(jbaase) online had found the solution after some hard time given by Logitech's customer support. He was finally told that such support(something to do with twain drivers) was removed after version 10.5.
So fortunately, I managed to download a 10.5 version, and voila, it works!
This is a service I did for one of my client, NYGC, where we are building a Student PhotoID system. Now, the next thing is the hardest: building the database with Symbol's scanner support.