Searching found many answers along the lines of it depends on the device driver", but I don't think that it's that way here.
I have a cheap & nasty RFID tag reader. You just have to open notepad, touch a tag to the read and its serial number appears in notepad (I have not tried it in Linux).
Anyhoo, how can I programatically capture this serial number in VB.net (20088 express)?
Seem it work in keyboard emulation. You can try to create a simple form with a textbox and check if the serial number appears on it when the tag is read and then manage the textbox events to retrive the info and set the focus correctly.
This probably works using keyboard emulation. The reader is pretending (to the PC) to be a USB keyboard, and simply sending the keystrokes.
If so you could do various things to check the keyboard input in VB.net. For a quick-and-dirty test, I would simply create a blank form with a textbox, make sure the textbox has focus, and read a tag. If the text passes to the textbox then the RFID reader is just passing keystrokes in, and you can use the textbox events to read the data (remembering to set focus to the textbox when you expect input).
If your app needs to do something more sophisticated with the input keystrokes, or you don't want them appearing in the control, you can trap and handle the keystrokes as they happen - the standard KB article on how to do this is here: http://support.microsoft.com/kb/320583